As I have said since Tony Dungy retired, the Colts are not going to switch to a new defensive scheme. Indy will run the same Tampa-2 defense they have run since 2002. It will rely on pressure from the d-line with the LBers and DBs mostly dropping back into zone coverage. Jim Caldwell has made this clear:
"From a schematic standpoint offensively and defensively we do not anticipate any drastic changes, but here’s the thing you have to understand about football. Every year, we take a total review and take a look at everything that we’ve done and often times there’s little tweaking that goes on because of the fact that maybe the opposition had caught on to a certain phase offensively or defensively or maybe your kicking game, so you have to make some adjustments there."
So, if anyone is crying that the Colts are still going to run a Tampa-2 and not switch to the flavor of the month defense (3-4 Zone Blitz), kindly dry your tears, suck it up, and soldier on. The flavor of the year two years ago was Tampa-2 defense because two teams with Tampa-2s faced each other. A year ago, people saw the Giants 4-3 Blitz destroy Tom Brady and the Patriots and wanted to switch to that. Now, after seeing two Zone Blitz defenses routinely give up big plays in the Super Bowl, people somehow want to switch to that. God knows why.
Like all established defensive schemes, when new coaches step in they like to make tweaks to the system so it fits their personality. Mike Tomlin tweaked Dick Lebeau's Zone Blitz by incorporating smaller, faster linebackers into the fold. There was less emphasis on fooling people and more placed on technique. Indeed, Tomlin is very much a Dungy disciple.
Like Tomlin with Pittsburgh's defense, Jim Caldwell will tweak the well-established defense in Indianapolis. One of the ways he may do this is by inserting larger linebackers into the defense who are less effective at coverage but much better at stopping the run and, perhaps, blitzing. From Pro Football Weekly:
In ’09, the Colts are banking on Philip Wheeler performing as well at outside linebacker as Pollak did at guard. A middle linebacker his last two seasons at Georgia Tech, Wheeler was selected with the understanding that the Colts envisioned him manning an OLB post. Following a rookie campaign that amounted to little more than a glorified redshirt season, Wheeler needs to hit the turf running on the outside in ’09.
One of the reasons Freddie K.O. and Tyjuan Hagler were let go is because the Colts invested a 3rd round pick in Wheeler. Unlike Keiaho and Hagler, Wheeler is 6'2 and weighs in at about 240 pounds. That's a big boy for a Tampa-2 linebacker. In the draft, the Colts may look for similar LBers in an effort to make the run defense more stout.
The draw back is the LBer coverage might suffer. This could put more pressure on the DBs and force them to play more man than Cover-2 or Cover-3. Or we could see a big improvement in Wheeler's coverage skills, giving Indy a big, fast guy who can tackle, hit, and cover. Wheeler is also a very good blitzer. One of the things some Tampa-2 defenses are starting to do is blitz their linebackers more. Another tweak, which was used against the Jaguars in December last year, was standing Raheem Brock up as a DT, and then having him swing around he outside the tackle in order to get pressure.
Regardless of the tweaks, the same basic philosophy wil remain: Three technique defensive line with the MIKE backer dropping straight back into coverage. The DBs will play mostly zone. It will be interesting to see if Indy moves to draft "Wheeler-like" players. Draft prospects like Clay Matthews seem to fit the bill.