The Immediate Impact Defense's Have When Switching From a 4-3 to a 3-4 Defense

Many teams have switched from the traditional 4-3 base defense to the 3-4 defense in the past 10 or so years. The Texans will be making the switch for 2011. This interests us because, as we all know, Houston has an elite offense, but had the league’s worst defense in 2010. If their defense can be so good as average in 2011, and they maintain similar production from their offense, than they will be in the playoffs and a serious contender for the super bowl. The Texans have disappointed everyone over the years. And now it seems people are done with them. But this study will show some interesting information.

We went back to 1999 and listed the team’s that switched from a 4-3 to 3-4 in this time period and how they fared the season before and the very next season. We only want to see the immediate impact a switch from the 4-3 to 3-4 has on a team.

So we listed many of their defensive stats for the season prior to each team’s switch and the season after. From there, we could make a verdict on whether the switch had a:

1. Large Improvement

1. Slight Improvement

3. No Improvement or Decline

4. Slight Decline

5. Large Decline

As for the format of the stats, we’ll list it here:

Team Defense (4-3/3-4): Record, Points per Game Allowed, Turnovers Forced, Yards per Play, 1^st Downs Allowed, Pass Yards Allowed, Pass TDs Allowed, Interceptions Forced, Yards per Attempt allowed, QB Rating allow, Sacks, Rush Yards Allowed, Rush TDs Allowed, Yards per Carry Allowed, 3^rd Down Defense Stop Percentage

- We have their league rank that year in parenthesis

Ok now, let’s get started. We went from the AFC East to NFC West in order of division, not in any other particular order.

New York Jets

The Jets installed a 3-4 defense in 2006 with new head coach Eric Mangini. Previous coach Herm Edwards employed a 4-3, Tampa-2 defense.

2005 Defense (4-3): 4-12 rec, 22.2 PPG allowed (23^rd), 28 turnovers (15^th), 4.7 Yds/Play (5^th), 321 1^stD (27^th), 2,755 Pass Yds (2^nd), 17 TDs (6^th), 21 INTs (5^th), 6.4 YPA (8^th), 73.1 QB Rtg. (6^th), 30 Sks (25^th), 2,185 Rush Yds (29^th), 19 TDs (27^th), 3.9 YPC (12^th), 42% 3rdD (28^th)

2006 Defense (3-4): 10-6 rec, 18.4 PPG allowed (6^th), 25 turnovers (24^th), 5.2 Yds/Play (16^th), 312 1stD (22^nd), 3,222 Pass Yds (14^th), 19 TDs (12^th), 16 INTs (17^th), 6.5 YPA (8^th), 78.0 QB Rtg. (12^th), 35 Sks (17^th), 2,184 Rush Yds (24^th), 14 TDs (19^th), 4.6 YPC (27^th), 36% 3rdD (10^th)

Overall, the defense had a slight improvement in their switch from the 4-3 to 3-4 in the first season. New York had an elite pass defense in 2005, and although that declined a bit when they switched to the 3-4 the next year, the Jets still had a top 10 pass defense. Their bad rush defense did not improve, but overall, we have to consider this a slight improvement because of their improved pass rush, PPG allowed, and their much improved 3^rd down defense.

Verdict: Slight Improvement

New England Patriots

Bill Bellichick was hired in 2000 for the Patriots, but they didn’t make the switch from the 4-3 to the 3-4 until 2003.

2002 Defense (4-3): 9-7 rec, 21.6 PPG allowed (17^th), 29 turnovers (16^th), 5.2 Yds/Play (19^th), 315 1stD (22^nd), 3,179 Pass Yds (11^th), 23 TDs (20^th), 18 INTs (12^th), 6.4 YPA (9^th), 78.2 QB Rtg. (15^th), 34 Sks (20^th), 2,198 Rush Yds (31^st), 17 TDs (23^rd), 4.7 YPC (29^th), 43% 3rdD (26^th)

2003 Defense (3-4): 14-2 rec, 14.9 PPG allowed (1^st), 41 turnovers (2^nd), 4.4 Yds/Play (4^th), 293 1stD (17^th), 3,232 Pass Yds (15^th), 11 TDs (1^st), 29 INTs (1^st), 5.6 YPA (1^st), 56.2 QB Rtg. (1^st), 41 Sks (6^th), 1,434 Rush Yds (4^th), 10 TDs (8^th), 3.6 YPC (6^th), 34% 3rdD (7^th)

Bellichick’s philosophy was the 3-4 defense, but he didn’t implement it until 2003 when he acquired all the right pieces. The Patriots had an average defense in 2002 with their 4-3. They had an above average pass defense and a well-below average run defense. Their switch to the 3-4 improved the pass defense from borderline elite to the best in the game, and the switch also drastically improved their run defense from a bottom dwelling unit to top 10. The switch helped propel New England to a Lombardi Trophy in 2003.

Verdict: Large Improvement

Miami Dolphins

After a 1-15 2007 season, the Dolphins hired Tony Sporano and Bill Parcells to rebuild the team. The Dolphins switched from a 4-3 to a 3-4 in 2008.

2007 Defense (4-3): 1-15 rec, 27.3 PPG allowed (30^th), 22 turnovers (30^th), 5.6 Yds/Play (29^th), 318 1stD (27^th), 3,019 Pass Yds (4^th), 28 TDs (28^th), 14 INTs (27^th), 7.8 YPA (31^st), 92.4 QB Rtg. (29^th), 30 Sks (24^th), 2,456 Rush Yds (32^nd), 18 TDs (30^th), 4.5 YPC (29^th), 47% 3rdD (32^nd)

2008 Defense (3-4): 11-5 rec, 19.8 PPG allowed (9^th), 30 turnovers (5^th), 5.4 Yds/Play (22^nd), 296 1^stD (15^th), 3,644 Pass Yds (25^th), 18 TDs (9^th), 18 INTs (8^th), 7.0 YPA (20^th), 77.0 QB Rtg. (9^th), 40 Sks (8^th), 1,620 Rush Yds (10^th), 10 TDs (11^th), 4.2 YPC (19^th), 38% 3rdD (10^th)

The Dolphins showed a large improvement from their 2007 defense, which was one of the worst in the NFL. The pass defense stiffened up as well as the pass rush. In addition, the run defense which was one of the worst in the league in 2007 improved to an above average unit. Overall, they improved in nearly every area.

Verdict: Large Improvement

Buffalo Bills

The Bills made the switch from the 4-3 to the 3-4 when Chan Gailey took over last year.

2009 Defense (4-3): 6-10 rec, 20.4 PPG allowed (16^th), 33 turnovers (6^th), 5.0 Yds/Play (7^th), 310 1stD (23^rd), 2,948 Pass Yds (2^nd), 14 TDs (4^th), 28 INTs (2^nd), 6.0 YPA (2^nd), 61.1 QB Rtg. (2^nd), 32 Sks (19^th), 2,501 Rush Yds (30^th), 19 TDs (28^th), 4.7 YPC (30^th), 40% 3rdD (24^th)

2010 Defense (3-4): 4-12 rec, 26.6 PPG allowed (28^th), 22 turnovers (27^th), 5.4 Yds/Play (19^th), 335 1^stD (28^th), 3,072 Pass Yds (3^rd), 28 TDs (27^th), 11 INTs (29^th), 6.9 YPA (14^th), 92.6 QB Rtg. (28^th), 27 Sks (29^th), 2,714 Rush Yds (32^nd), 18 TDs (27^th), 4.8 YPC (32^nd), 43% 3rdD (30^th)

The Bills had an above average defense in 2009. They were arguably the toughest team to pass on in the entire NFL, ranking in the top 5 each of the pass defense categories. In rush defense, they were one of the bottom 5 units in the NFL. In their switch to the 3-4 in 2010, the Bills pass defense became a below average unit. Look no further than the 92.6 QB Rating they posted in 2010, which was 31.5 points above their 2009 total. Not only that, their rush defense actually went from a bottom 5 unit to the worst in the NFL. Their pass rush and 3^rd down defense also deteriorated. Overall, the Bills went from an above average defense to a bottom 5 defense in their switch.

Verdict: Large Decline

Baltimore Ravens

The Ravens originally had a hybrid system in place dating back to 2000. They mainly ran the 4-3 in that time with some 3-4 mixed in, however, they fully made the switch after the 2001 season.

2001 Defense (4-3): 10-6 rec, 16.6 PPG allowed (4^th), 28 turnovers (17^th), 4.4 Yds/Play (1^st), 262 1stD (5^th), 3,035 Pass Yds (8^th), 16 TDs (10^th), 16 INTs (17^th), 6.0 YPA (1^st), 72.8 QB Rtg. (12^th), 45 Sks (9^th), 1,411 Rush Yds (4^th), 10 TDs (12^th), 3.4 (2^nd), 31% 3rdD (3^rd)

2002 Defense (3-4): 7-9 rec, 22.1 PPG allowed (19^th), 31 turnovers (9^th), 5.0 Yds/Play (11^th), 316 1stD (23^rd), 3,591 Pass Yds (26^th), 16 TDs (4^th), 25 INTs (2^nd), 6.7 YPA (21^st), 73.4 QB Rtg. (5^th), 33 Sks (22^nd), 1,762 Rush Yds (13^th), 17 TDs (23^rd), 3.7 YPC (1^st), 40% 3rdD (21^st)

The Ravens allowed more point per game, but neither the pass defense nor run defense significantly declined. Both were elite units in 2001, and had a small decline the next season, but nothing major. The main factor for the defenses overall decline can be charged to their decline in pass rush and inability to get key stops on 3^rd down.

Verdict: Slight Decline

Cleveland Browns

Former defensive coordinator of the Patriots Romeo Crenell took over in Cleveland in 2005 and installed his 3-4 philosophy immediately.

2004 Defense (4-3): 4-12 rec, 24.4 PPG allowed (24^th), 28 turnovers (20^th), 5.1 Yds/Play (12^th), 307 1stD (19^th), 2,901 Pass Yds (5^th), 17 TDs (6^th), 15 INTs (19^th), 6.7 YPA (9^th), 79.0 QB Rtg. (16^th), 32 Sks (27^th), 2,314 Rush Yds (32^nd), 22 TDs (32^nd), 4.3 YPC (21^st), 36% 3rdD (15^th)

2005 Defense (3-4): 6-10 rec, 18.8 PPG allowed (11^th), 23 turnovers (25^th), 5.0 Yds/Play (13^th), 292 1stD (15^th), 2,867 Pass Yds (4^th), 19 TDs (16^th), 15 INTs (22^nd), 6.4 YPA (7^th), 78.2 QB Rtg. (16^th), 23 Sks (32^nd), 2,202 Rush Yds (30^th), 11 TDs (11^th), 4.2 YPC (25^th), 40% 3rdD (20^th)

None of the stats significantly improved besides scoring allowed, which went up 13 spots the year after the Browns switched to the 3-4. Overall, they allowed less 1^st downs and Yds per play. Their pass defense stayed about the same while their run defense improved by a bit. Their 3^rd down defense, turnovers, and pass rush declined. In the grand scheme though, we have to consider this a slight improvement because of the PPG allowed.

Verdict: Slight Improvement

Jacksonville Jaguars

Before the 1999 season, Tom Coughlin, the head coach of the Jaguars, fired Dick Jauron and hired Dom Capers to take over the defense. Capers immediately switched to his preferred 3-4 style of defense.

1998 Defense (4-3): 11-5 rec, 21.1 PPG allowed (17^th), 30 turnovers (15^th), 5.3 Yds/Play (24^th), 309 1stD (23^rd), 3,559 Pass Yds (23^rd), 23 TDs (17^th), 13 INTs (23^rd), 6.5 YPA (8^th), 80.1 QB Rtg. (20^th), 30 Sks (27^th), 2,000 Rush Yds (22^nd), 9 TDs (8^th), 4.4 YPC (26^th), 36% 3rdD (11^th)

1999 Defense (3-4): 14-2 rec, 13.6 PPG allowed (1^st), 30 turnovers (17^th), 4.6 Yds/Play (4^th), 248 1stD (3^rd), 2,890 Pass Yds (3^rd), 18 TDs (6^th), 19 INTs (12^th), 6.3 YPA (5^th), 71.0 QB Rtg. (12^th), 57 Sks (2^nd), 1,444 Rush Yds (7^th), 6 TDs (4^th), 3.9 YPC (13^th), 34% 3rdD (9^th)

The Jags had a slightly below average defense when Dom Capers took over. Capers transformed this defense into top 5 in the NFL with his 3-4. The big improvement was in the pass rush, which went up 27 sacks from one season, an unbelievable improvement. With that, the pass defense improved. The rush defense, which was a bad one in the 4-3, also improved during the transformation to an above average unit. The scoring allowed improved to the best in the NFL.

Verdict: Large Improvement

San Diego Chargers

Before the 2004 season, Marty Schottenheimer hired Wade Phillips, who will transition the Texans to a 3-4 in 2011, to be his defensive coordinator.

2003 Defense (4-3): 4-12 rec, 26.7 PPG allowed (31^st), 20 turnovers (31^st), 5.2 Yds/Play (18^th), 326 1stD (30^th), 3,375 Pass Yds (21^st), 36 TDs (32^nd), 13 INTs (28^th), 6.8 YPA (18^th), 94.3 QB Rtg. (32^nd), 30 Sks (25^th), 2,218 Rush Yds (26^th), 12 TDs (14^th), 4.3 YPC (20^th), 42% 3rdD (29^th)

2004 Defense (3-4): 12-4 rec, 19.6 PPG allowed (11^th), 33 turnovers (9^th), 5.4 Yds/Play (22^nd), 320 1stD (25^th), 4,053 Pass Yds (31^st), 19 TDs (11^th), 23 INTs (3^rd), 6.9 YPA (16^th), 76.6 QB Rtg. (9^th), 29 Sks (29^th), 1,307 Rush Yds (3^rd), 15 TDs (22^nd), 3.7 YPC (7^th), 35% 3rdD (10^th)

This is a very relevant case in our study, because Wade Phillips is taking over a squad that had similar problems to the Texans. The Chargers were one of the league’s worst in 2003, allowing a 94.3 QB Rtg. and 36 TDs through the air. However, they really improved in those two areas as well as forcing more interceptions and an improved run stopping unit. The 3-4 switch propelled the Chargers to a 12-4 record, something the Texans will be hoping to do. The Chargers became a solid defense, and we know that if Wade Phillips can have the same effect on Houston in 2011, we’ll see them making their first playoff appearance in franchise history.

Verdict: Large Improvement

Denver Broncos

The Broncos hired Josh McDaniels in 2009. McDaniels was taking over one of the league’s worst defenses, and he hired Mike Nolan to be his defensive coordinator. Nolan switched from the 4-3 which was employed in ’08 to a 3-4.

2008 Defense (4-3): 8-8 rec, 28.0 PPG allowed (30^th), 13 turnovers (32^nd), 6.1 Yds/Play (32^nd), 327 1stD (29^th), 3,656 Pass Yds (26^th), 20 TDs (14^th), 6 INTs (31^st), 7.7 YPA (28^th), 98.5 QB Rtg. (31^st), 26 Sks (26^th), 2,337 Rush Yds (27^th), 26 TDs (31^st), 5.0 YPC (31^st), 44% 3rdD (25^th)

2009 Defense (3-4): 8-8 rec, 20.2 PPG allowed (12^th), 30 turnovers (9^th), 5.0 Yds/Play (7^th), 290 1stD (13^th), 2,981 Pass Yds (3^rd), 18 TDs (9^th), 17 INTs (14^th), 6.3 YPA (4^th), 75.0 QB Rtg. (8^th), 39 Sks (10^th), 2,059 Rush Yds (26^th), 11 TDs (11^th), 4.5 YPC (27^th), 37% 3rdD (13^th)

The Broncos showed a large improvement in their switch. They started the season 6-0 with one of the league’s best defenses, but stumbled in the end of the season. In 2008, Denver had one of the league’s worst pass defenses. After the switch, they had a top 10 unit. The turnover and sack totals also drastically improved, as well as a slightly improved, though still below average run defense.

Verdict: Large Improvement

Kansas City Chiefs

After a 2-14 2008 season, the Chiefs fired head coach Herm Edwards and brought in Todd Haley. Scott Pioli was also brought in. They switched to a 3-4 defense in 2009.

2008 Defense (4-3): 2-14 rec, 27.5 PPG allowed (29^th), 29 turnovers (11^th), 6.0 Yds/Play (29^th), 344 1stD (31^st), 3,748 Pass Yds (28^th), 21 TDs (19^th), 13 INTs (15^th), 7.3 YPA (25^th), 91.1 QB Rtg. (25^th), 10 Sks (3nd), 2,543 Rush Yds (30^th), 25 TDs (29^th), 5.0 YPC (31^st), 47% 3rdD (32^nd)

2009 Defense (3-4): 4-12 rec, 26.5 PPG allowed (29^th), 28 turnovers (15^th), 5.8 Yds/Play (30^th), 318 1stD (26^th), 3,707 Pass Yds (22^nd), 25 TDs (21^st), 15 INTs (15^th), 7.6 YPA (26^th), 87.1 QB Rtg. (20^th), 22 Sks (31^st), 2,504 Rush Yds (31^st), 18 TDs (26^th), 4.7 YPC (31^st), 38% 3rdD (15^th)

The Chiefs had one of the league’s worst defenses in 2008. The switch to the 3-4 didn’t do much for them immediately. They wouldn’t reap the benefits until 2010. Their defense didn’t improve or decline in 2009. The stats hovered around the bottom 10 defenses in the NFL both seasons.

Verdict: No Improvement or Decline

Dallas Cowboys

Bill Parcells was brought in for the Cowboys in 2003, but they didn’t switch full time to the 3-4 until Parcells acquired the right talent and players to fit the system. The switch came in 2005.

2004 Defense (4-3): 6-10 rec, 25.3 PPG allowed (27^th), 22 turnovers (26^th), 5.5 Yds/Play (25^th), 297 1^stD (12^th), 3,521 Pass Yds (21^st), 31 TDs (29^th), 13 INTs (25^th), 7.4 YPA (23^rd), 94.2 QB Rtg. (27^th), 33 Sks (26^th), 1,764 Rush Yds (10^th), 14 TDs (20^th), 4.2 YPC (17^th), 39% 3rdD (22^nd)

2005 Defense (3-4): 9-7 rec, 19.2 PPG allowed (12^th), 26 turnovers (22^nd), 5.1 Yds/Play (19^th), 256 1stD (2^nd), 3,083 Pass Yds (11^th), 18 TDs (12^th), 15 INTs (21^st), 6.7 YPA (15^th), 75.1 QB Rtg. (9^th), 37 Sks (14^th), 1,731 Rush Yds (15^th), 13 TDs (17^th), 4.2 YPC (21^st), 35% 3rdD (6^th)

The Cowboys had a noticeable improvement across the board in their first year switching to the 3-4. The pas defense took great strides, going from one of the bottom 5 units to an above average unit. The rush defense stayed about the same, but the pass rush, turnovers, and 3^rd down defense also improved.

Verdict: Large Improvement

Washington Redskins

The Redskins transitioned to the 3-4 scheme in 2010 after they hired Mike Shannahan to take over.

2009 Defense (4-3): 4-12 rec, 21.0 PPG allowed (18^th), 17 turnovers (32^nd), 5.1 Yds/Play (10^th), 280 1stD (7^th), 3,316 Pass Yds (9^th), 19 TDs (13^th), 11 INTs (26^th), 7.0 YPA (18^th), 85.7 QB Rtg. (18^th), 40 Sks (8^th), 1,799 Rush Yds (16^th), 10 TDs (9^th), 4.0 YPC (8^th), 40% 3rdD (21^st)

2010 Defense (3-4): 6-10 rec, 23.6 PPG allowed (21^st), 27 turnovers (16^th), 5.9 Yds/Play (30^th), 326 1stD (25^th), 4,187 Pass Yds (31^st), 23 TDs (17^th), 14 INTs (20^th), 7.5 YPA (28^th), 89.6 QB Rtg. (25^th), 29 Sks (26^th), 2,041 Rush Yds (26^th), 15 TDs (24^th), 4.6 YPC (25^th), 35% 3rdD (8^th)

The Redskins did not have a smooth transition to the 3-4. They had a solidly above average defense in 2009, which turned into a below average defense in 2010. They did improve in turnovers and 3^rd down defense, and their scoring didn’t drastically decline, but the major decline was seen in their rush defense, which turned into a well below average unit after having a solid one in 09. The pass rush and overall pass defense was not up to the 2009 level either, so we have to call this a large decline.

Verdict: Large Decline

Green Bay Packers

The Packers made the switch to the 3-4 in 2009 when Dom Capers took over as defensive coordinator.

2008 Defense (4-3): 6-10 rec, 23.8 PPG allowed (22^nd), 28 turnovers (12^th), 5.3 Yds/Play (16^th), 295 1stD (14^th), 3,244 Pass Yds (12^th), 22 TDs (22^nd), 22 INTs (4^th), 6.5 YPA (7^th), 71.9 QB Rtg. (4^th) 27 Sks (25^th), 2,105 Rush Yds (26^th), 20 TDs (27^th), 4.6 YPC (26^th), 38% 3rdD (14^th)

2009 Defense (3-4): 11-5 rec, 18.6 PPG allowed (7^th), 40 turnovers (1^st), 4.8 Yds/Play (2^nd), 272 1^stD (3^rd), 3,218 Pass Yds (5^th), 29 TDs (29^th), 30 INTs (1^st), 6.4 YPA (5^th), 68.8 QB Rtg. (4^th), 37 Sks (11^th), 1,333 Rush Yds (1^st), 5 TDs (1^st), 3.6 YPC (3^rd), 36% 3^rdD (7^th)

The Packers had a very solid defense in 2008, but it truly became elite in 2009 with the switch to the 3-4. The huge improvement was in their rush defense, which struggled in 2009 but became arguably the best run stopping unit in the NFL after their switch to the 3-4. The pass defense, which was already elite, actually became better with an improved pass rush and a better turnover rate. Overall, the Packers became a top 3 defense in the NFL after their switch to the 3-4. Before it, they were in the 12-16 range.

Verdict: Large Improvement

Atlanta Falcons

The Falcons had a short lived flirtation with a 3-4 defense in the earlier part of this decade while Wade Phillips commanded the defense, prior to his transition of the Chargers defense.

2001 Defense (4-3): 7-9 rec, 23.6 PPG allowed (24^th), 30 turnovers (14^th), 6.1 Yds/Play (31st), 298 1^stD (21^st), 3,902 Pass Yds (30^th), 29 TDs (28^th), 18 INTs (13^th), 8.0 YPA (30^th), 93.3 QB Rtg. (30^th), 37 Sks (19^th), 1,943 Rush Yds (21^st), 13 TDs (10th), 4.8 YPC (31^st), 46% 3rdD (31^st)

2002 Defense (3-4): 9-6-1 rec, 19.6 PPG allowed (8^th), 39 turnovers (2^nd), 5.3 Yds/Play (23^rd), 288 1stD (10^th), 3,287 Pass Yds (16^th), 23 TDs (19^th), 24 INTs (3^rd), 7.0 YPA (25^th), 72.8 QB Rtg. (4^th), 47 Sks (5^th), 2,047 Rush Yds (23^rd), 12 TDs (7^th), 4.6 YPC (28^th), 40% 3rdD (20^th)

This is another very relevant case because of Wade Phillips. Again, Wade took over a defense that struggled in defending the pass especially. Atlanta also had some trouble stopping the run. The pass defense significantly improved, going from a 93.3 QB Rtg. to a 72.8 in one year and also adding 10 sacks. There was good improvement shown across the board, except for the rushing game, which more or less stayed the same. But with the improvement in scoring, turnovers, 3^rd down defense, and pass defense, we have to call this a major improvement.

Verdict: Large Improvement

San Francisco 49ers

The 49ers began their switch to the 3-4 defense in 2005 when Mike Nolan took over.

2004 Defense (4-3): 2-14 rec, 28.2 PPG allowed (32^nd), 21 turnovers (28^th), 5.4 Yds/Play (21^st), 322 1stD (27^th), 3,486 Pass Yds (19^th), 27 TDs (23^rd), 9 INTs (29^th), 7.5 YPA (25^th), 96.5 QB Rtg. (29^th), 29 Sks (30^th), 1,995 Rush Yds (20^th), 22 TDs (32^nd), 4.0 YPC (13^th), 40% 3rdD (23^rd)

2005 Defense (3-4): 4-12 rec, 26.8 PPG allowed (29^th), 26 turnovers (24^th), 5.7 Yds/Play (31^st), 335 1stD (30^th), 4,427 Pass Yds (32^nd), 28 TDs (31^st), 16 INTs (18^th), 8.0 YPA (32^nd), 94.2 QB Rtg. (30^th), 28 Sks (28^th), 1,832 Rush Yds (18^th), 19 TDs (28^th), 3.8 YPC (11^th), 38% 3rdD (18^th)

The 49ers didn’t really improve or decline with their switch to the 3-4. The already poor pass defense actually got worse, as they stayed the same in their pass rush but added more interceptions. The run defense got slightly better, as did the 3^rd down defense, but the yards per play average went up to 31^st in the NFL. You can argue they made a slight improvement overall, but we aren’t going to.

Verdict: No Improvement or Decline

Arizona Cardinals

Ken Wisenhunt took over as head coach of the Cardinals in 2007 and transitioned Arizona to a 3-4 defense.

2006 Defense (4-3): 5-11 rec, 24.3 PPG allowed (29^th), 33 turnovers (6^th), 5.5 Yds/Play (29^th), 331 1stD (31^st), 3,694 Pass Yds (30^th), 21 TDs (16^th), 16 INTs (19^th), 7.5 YPA (31^st), 85.4 QB Rtg. (24^th), 38 Sks (13^th), 1,897 Rush Yds (16^th), 16 TDs (26^th), 4.1 YPC (16^th), 41% 3rdD (21^st)

2007 Defense (3-4): 8-8 rec, 24.9 PPG allowed (27^th), 29 turnovers (16^th), 5.2 Yds/Play (19^th), 298 1stD (17^th), 3,716 Pass Yds (28^th), 26 TDs (25^th), 18 INTs (13^th), 6.9 YPA (15^th), 85.8 QB Rtg. (22^nd), 36 Sks (15^th), 1,567 Rush Yds (9^th), 13 TDs (22^nd), 3.9 YPC (11^th), 40% 3rdD (17^th)

The Cardinals showed a slight improvement with their switch to the 3-4 in 2007. Their pass defense remained similar with very little change, but it was in their rush defense were they showed some real improvement. They allowed 300+ less yards in 2007, as well as 3 TDs and 0.2 YPC less. Their 3^rd down defense also improved a touch.

Verdict: The slightest of Improvements

Now, some analysis:

Overall –

3 Slight Improvements

8 Large Improvements

11 Total Improvements

1 Slight Decline

2 Large Declines

3 Total Declines

2 No Improvement or Declines

So 16 teams – 11 improvements (68.8%), 3 declines (18.8%), 2 no changes (12.5%)

The farthest we went back in this study was the Jaguars switch in 1999 because we don’t have enough information to go back prior to then. Either way, we feel this was a successful study. Wade Phillips appeared in two of these cases, and there was a large improvement seen in both cases (Falcons and Chargers). Again, the main reason we did this was try to predict the Texans 2011 season based on prior 3-4 switches from the 4-3 and the immediate impact they had on defenses.

Of course, we saw the cases vary on there are many reasons it could. But the general consensus is that there will be an improvement. And with Wade Phillips commanding the defense, the odds are that it will be a large improvement. With the elite offense that Houston has, this should be enough to get them into the playoffs, and easily could be enough to make them a contender for the Super Bowl in 2011. Take a look:

Houston Texans

2010 Defense (4-3): 6-10 rec, 26.7 PPG allowed (29^th), 18 turnovers (31^st), 6.0 Yds/Play (31^st), 352 1stD (31^st), 4,280 Pass Yds (32^nd), 33 TDs (32^nd), 13 INTs (23^rd), 8.2 YPA (31^st), 100.5 QB Rtg. (32^nd), 30 Sks (23^rd), 1,751 Rush Yds (13^th), 16 TDs (26^th), 4.0 YPC (11^th), 40% 3rdD (25^th)

2011 Defense (3-4): ???????????

Stay tuned for our projections on the Texans, which will be based heavily on evidence such as this. We should expect a slight/large improvement, but check back in to see the actual projections we have for Houston’s defense and entire team in 2011.