Since Tony Dungy came to the Bucs, the team has employed a fairly basic scheme on defense, a Cover 2 variant that worked so well it was named after the team itself and became known as Tampa 2. The system is very simple, and Dungy was loathe to alter the scheme too much for individual opponents. He stayed in the base defense for most of a game, blitzing less than anyone else in the league. When Dungy left and Kiffin could take full control of the defense this philosophy didn't change, although Kiffin was more willing to alter his defense to fit specific situations. The base Tampa 2 has been a part of the Bucs' identity for a long time, and despite a move away from the scheme during Jim Bates' time as a DC it continues to be so. But Raheem Morris himself is altering the scheme heavily right now.
The advantage of sticking to a simple base scheme is that it's easy to teach and run. Since there's little variation, the only defensive breakdowns will happen because of player incompetence, not because of confusion. Moreover, it's easier to plug in inexperienced players as they'll be able to assimilate the defense quickly. There's also a big drawback, though: you can't outscheme opponents, so you have to outplay them. If you want to beat an opponent, you have to have better talent, and if you don't have that talent your defense will suffer. That's what we saw last year, when the Bucs had superior players at cornerback, but not at any other defensive position. Contrast that with a defense like Bill Belichick's, which tries to outwit opponents at every turn. The downside there is, of course, that you run the risk of confusing your own players as well as the opponent's, leading to breakdowns in coverage.
What we saw last year for the Bucs was a combination of the two. At the beginning of the year the scheme remained fairly close to Tampa 2, with a few more blitzes thrown in than usual. But as the year progressed Raheem Morris started to create more complex schemes for his players, employing a variety of creative blitzes, zone blitzes and coverages. He rarely took great risks in coverage to create pressure though, as Raheem seems to be intent on protecting its secondary at all times. The exception to that rule is Aqib Talib, the one player he's comfortable with on an island with no help.
I think in the future we'll see Raheem start to mix in more and more creative schemes, trying to outscheme opponents. It's tough to do so when your team is filled with young, inexperienced players, but as players assimilate schemes Raheem will push his defense further and further. He has to be careful that he doesn't push players too far, and that he keeps the specific skills of every player in mind. For instance, the many zone blitzes he ran at the end of the year were not entirely ineffective but still somewhat stunning, since they put his worst pass defenders in coverage, and his worst pass rusher (Barrett Ruud) in position to blitz. That caused some confusion for blocking schemes and actually got the Bucs some decent pressure. Unfortunately they'd also lead to Stylez G. White trying to cover Calvin Johnson. That didn't end very well. Raheem has to find a balance between trying to outscheme his opponents and using his players to the best of their abilities, and I don't think he found the right balance in 2010.