When talking about the Bucs Tight Ends, Kellen Winslow Jr. obviously jumps to the fore. He was Josh Freeman's security blanket in 2009, and in 2010 he was a consistent producer in the passing game. Although he didn't start off too quickly, he finished up the year with some very strong performances including a 7-catch, 98-yard 2 touchdown effort against the Seahawks. The defensive attention the big pass-catcher got early in the year allowed Mike Williams and others some extra freedom, and when coverages started to adjust to Mike Williams, Kellen Winslow got a little more freedom to move and his numbers quickly improved.
Unfortunately, Kellen Winslow is not a good run blocker, so he's not particularly versatile. If Kellen Winslow is in as the lone tight end, the Bucs are a lot less likely to run the ball than when John Gilmore is in there. John Gilmore's specialty is, of course, run blocking - and he's pretty good at that, but he's not being paid to catch passes. Despite that, he had a career year as a pass-catcher: 13 catches for 160 yards and a touchdown. Not exactly great production of course, but Gilmore caught the balls he had to catch. Gilmore is a consistent performer, an anonymous player that's still valuable to the team.
One player that was another fairly anonymous producer was Jerramy Stevens. The former Seahawk was a competent pass-catcher behind Kellen Winslow, but not a dynamic threat by any means. And he was also weak as a run-blocker. All that didn't kill his tenure with the team, though: getting arrested for possession with intent to distribute did. Jerramy Stevens wasn't any better than replacement level, so that wasn't a big loss. And it left some room for Ryan Purvis to step up.
Purvis turned out to be yet another fairly anonymous but consistent producer. He was a good blocker who caught the balls he had to catch. Basically he was John Gilmore Jr. In fact, I wouldn't be surprised if the Bucs don't resign John Gilmore because they think Purvis can step into his role fulltime, and they can have an unknown like Nathan Overbay perform well as a backup.
The team now has blocking tight ends and one pass-catching tight end, but it doesn't have a tight end that can do both well. That kind of versatility is very valuable, as it allows you to use your personnel packages in different ways. The Patriots used this strategy to steamroll opponents, with personnel groups with Aaron Hernandez and Gronkowski could line up in strong running formations as well as full spread formations. That kind of versatility can create a lot of mismatches for the offense, and it's the kind of versatility the Bucs lack at the tight end position.