This has been an offseason of considerable defensive change in the NFL, but it hasn't stopped with the three teams making full or partial transitions from 4-3 to 3-4 schemes -- the Green Bay Packers, Denver Broncos and Kansas City Chiefs.
Eighteen other clubs are making adjustments on defense that don't entail an all-out switch of their base scheme but are significant nonetheless.
The adjustments have resulted from coaching changes and/or defensive-rooted head coaches choosing to be more hands on with their area of expertise. (The total number of teams actually could grow to 19, with Philadelphia Eagles defensive coordinator Jim Johnson, one of the most innovative thinkers in the game, taking an indefinite leave as he battles cancer).
Perhaps the most dramatic change in a team's defense not altering its base scheme can be found with the Tampa Bay Buccaneers, who have a new head coach (Raheem Morris, who replaced Jon Gruden) and defensive coordinator (Jim Bates, who replaced Monte Kiffin). Dating back to when Tony Dungy was their head coach, the Bucs have exclusively employed a two-deep zone coverage look (aptly named the Tampa 2) that emphasizes speed over size and power. But no more. Although the Buccaneers will keep their 4-3 base and Morris is their former defensive backs coach who knows the Tampa 2 well, he's going to defer to Bates' approach that calls for big players who are stout at the point of attack.
"Are we going to do what Jim Bates does best? Yes," Morris said. "Does Jim Bates want to mix in some of the stuff Monte did? Yes. We'll have a mixture. It's more about the core beliefs than what (signals) you're calling. The physical, violent football team always wins. John Fox has done that in Carolina, Mike Tomlin in Pittsburgh, the Giants ... those physical, tough teams always win."
The Indianapolis Colts are another club that have long employed the Tampa 2. But now they, too, have a new head coach (Jim Caldwell, who replaced Dungy) and new defensive coordinator (Larry Coyer, who replaced Ron Meeks). Coyer has experience with the Tampa 2, but is likely to be more aggressive in rushing the passer than his predecessor.
"He'll modify what we need to modify, so there's going to be some tweaking, obviously," Caldwell said of Coyer.
Here's a closer look, in alphabetical order, of other teams undergoing one form of defensive change or another:
» Arizona Cardinals: Despite their Super Bowl run, the Cardinals no longer wanted to use the hybrid 3-4 scheme that Clancy Pendergast implemented as defensive coordinator. So he was fired (freeing him to employ the same hybrid 3-4 approach with the Chiefs) and replaced by former Cards linebackers coach Bill Davis, who will utilize more 3-4 concepts.
» Baltimore Ravens: Rex Ryan left as defensive coordinator to become head coach of the New York Jets. His replacement, Greg Mattison, will keep the 3-4 base, but it's hard to imagine anyone matching Ryan's unbridled aggressiveness and creativity when it comes to blitzing.
» Carolina Panthers: Ron Meeks, who replaced Mike Trgovac as defensive coordinator, is going to stick with the 4-3 base that has long been attached to head coach John Fox. But Meeks is going to bring his Tampa 2 in hopes of improving the defense's ability to prevent the big play; the Panthers gave up 13 touchdown passes in the final six games last season.
» Chicago Bears: Although Bob Babich will keep his title as defensive coordinator, head coach Lovie Smith is going to be more heavily involved in play-calling. Smith made his mark in coaching as a defensive coordinator and believes he can push the right buttons to improve his 4-3 defense, which ranked 21st in the NFL in total yards allowed and was 30th against the pass.
» Cleveland Browns: They have a new head coach (Eric Mangini, who replaced Romeo Crennel) and a new defensive coordinator (Rob Ryan, who replaced Mel Tucker). Although the Browns will continue to have a 3-4 defense and Mangini, Ryan, and Crennel are branches from the same Bill Belichick coaching tree, the new staff is expected to be more aggressive and creative in rushing the passer.
» Dallas Cowboys: Head coach Wade Phillips will serve as his own defensive coordinator, replacing Brian Stewart, who was fired after last season. Phillips was involved in the supervision of his 3-4 defense last season, but now he will run the defensive meetings, provide more instruction on defensive techniques, and continue with the play-calling that he took over last season.
» Detroit Lions: They'll no longer use the Tampa 2 that former coach Rod Marinelli, an ex-Bucs defensive assistant, employed. They'll stick with the 4-3. However, new coach Jim Schwartz and new defensive coordinator Gunther Cunningham are going to utilize a scheme that relies on larger defenders, especially on the interior of the line, and greater versatility in applying pressure on the quarterback.
» Houston Texans: Frank Bush was promoted from senior defensive assistant to replace Richard Smith as defensive coordinator. Bush will keep the 4-3 scheme, but he'll be tweaking personnel combinations in the front seven to make sure the four best pass-rushers are on the field in all passing situations.
» Jacksonville Jaguars: Under new defensive coordinator Mel Tucker, who replaced Gregg Williams, the Jaguars will still primarily be a 4-3 defense. But they will incorporate some 3-4 elements. Tucker previously oversaw the Browns' 3-4 scheme, but Jack Del Rio, whose coaching expertise is rooted in defense, will be more heavily involved in guiding the defense and will focus on doing a better job of handling the spread offenses the Jags often face in the AFC South.
» New Orleans Saints: They'll keep their 4-3 look, but new defensive coordinator Gregg Williams will employ a highly complex scheme that can be hard to grasp. Still, the Saints believe, with the strong player additions they've made to their defense in the offseason, Williams should be able to have a strong impact and finally provide the long-awaited complement to one of the league's more explosive offenses.
» New York Giants: Steve Spagnuolo left as defensive coordinator to become head coach of the St. Louis Rams. His replacement, Bill Sheridan, will continue to run a 4-3 scheme and has inherited plenty of talented players to make it highly successful. But Spagnuolo distinguished himself as one of the brightest defensive minds in the game, and Sheridan has an extremely tough act to follow.
» New York Jets: New head coach Rex Ryan replaces the 3-4 scheme of his predecessor, Eric Mangini, with a far more aggressive, blitz-happy version that new defensive coordinator Mike Pettine will help guide.
» Oakland Raiders: The challenge of new defensive coordinator John Marshall, who replaced Rob Ryan, is to figure out how to make this 4-3 defense stronger against the run. The improvement isn't likely to come from any of the existing players within the front seven, so Marshall has to be inventive with playing safeties close to the line of scrimmage.
» St. Louis Rams: This team had put the fortunes of its 4-3 scheme in the hands of mostly small and quick front-seven defenders, but not anymore. New coach Steve Spagnuolo likes larger and tougher guys up front, as does new defensive coordinator Ken Flajole, who was used to working with such players when he was linebackers coach in Carolina. Let the revamping begin.
» Tennessee Titans: OK, so coach Jeff Fisher has one of the best defensive minds the game has ever seen. Nevertheless, Jim Schwartz, who left as defensive coordinator to become head coach of the Lions, had a lot to do with helping to make the Titans' 4-3 scheme highly effective, especially when it came to generating pressure mainly from the defensive line. His replacement, former Titans secondary coach Chuck Cecil, faces a monstrous challenge trying to do that without dominant tackle Albert Haynesworth, who left for Washington in free agency.