When the Patriots bring in defensive players, there are two things they always look for: love of the game, and size. The Patriots draft size on defense, and their defense is built around big guys. Almost all their defensive linemen top 300 lbs and all their linebackers top 240 lbs, most of them even top 250 lbs. The Patriots built their championship teams on defense, so they know what they're doing in that regard.
The Buccaneers of the '90s did the exact opposite, though. They took speed over size every single time. Arguably the best Buccaneer ever, Derrick Brooks, was undersized. When he came out of college teams wanted to move him to the safety position because of his speed and his lack of size. But the Buccaneers drafted him as a linebacker, and that turned out fine. Warren Sapp wasn't that big for a defensive tackle, but he was incredibly fast for the position. Simeon Rice's game was built on speed. The Bucs used to build their defense around speed, so why should this change?
Well, there's another team that builds its team on speed: the Indianapolis Colts under Tony Dungy. Their defense has never been good, with the exception of the 2006 playoffs and 2007, when Bob Sanders was actually healthy. But their defense could never win games on its own, as their undersized team struggles to stop the run. They rely on Peyton Manning building a lead to force opponents to abandon the run and play to the defense's strength: pass defense. And that was visible for old Bucs defenses as well: the run defense was never as good as the pass defense.
When Raheem Morris took over the team, his first order of business was to hire Jim Bates to change the defense. Bates favored bigger front-seven players, and while his defensive experiment was a complete failure, Raheem did take away one thing from Bates: size matters. Although this hasn't filtered through to the defensive tackle position - neither Gerald McCoy nor Brian Price are particularly big, though they're hardly small - it has filtered through to the linebacker position. Geno Hayes was the type of linebacker the Bucs used to pick - undersized, but fast. The 6'1" 226 lb Florida State product is phsyically similar to Derrick Brooks (6'0" 235 lb), but he's the only one of his kind on the roster. Tyrone McKenzie, Dekoda Watson, Quincy Black, Adam Hayward, Niko Koutouvides and Barrett Ruud are all 240 lbs or more. Of course, the run defense is worse now than it ever was with an undersized roster. Clearly, size alone isn't the answer.
In the future, I expect this trend of increasing size to continue. When the Bucs started adding defensive ends and tackles during the season you could see it as well. Alex Magee is 298 lbs, which is huge for a 4-3 defensive end, and Doug Worthington and E.J. Wilson are barely smaller at 292 and 289 respectively. The one defensive tackle they added was Al Woods, again a big guy at 314 lbs. The Bucs aren't going to go to a 3-4 2-gap defense like the Patriots, but they are setting themselves up to run hybrid defenses with bigger players. Raheem Morris loves that schematic versatility, and I'm sure he hopes that size will help them stop the run better - but I'm not sure it actually will. It hasn't so far.