The Bucs had a bad defense last year. It wasn't as horrible as it was in 2009, but it was still pretty bad. The run defense really couldn't stop anyone, whereas the pass defense looked somewhat decent. And, of course, the defense was really inconsistent - they had some really bad first halves and then followed those up by shutting out the opposition in the second half. But what the Bucs almost never managed to do was force 3-and-outs.
In fact, according to Football Outsiders the Bucs forced the second-fewest 3-and-outs in the NFL: just 29. Only the Houston Texans and their abysmal pass defense did worse. This all goes back to the Bucs' inability to get off the field on third down. That was most obvious when Matt Ryan and Roddy White managed to convert a third-and-20 late in a close game. While the Bucs defense looked good at times, it's nowhere near the old days of forcing punts after 3 plays.
If the Bucs want to get back to playing good defense, they need to get off the field on third down. And to do so, they need to shut down the run on first and second down and finally get a pass rush going on third down. They never managed to do either in 2010, but they have focused on those aspects of the game in the draft. Their first two picks, Adrian Clayborn and Da'Quan Bowers, are terrific run defenders who should boost the pass rush - especially Bowers. The Bucs are putting the talent in place, but they need to get the play out of them too.