Zone defenses and blitz defenses both have their pros and cons.
Teams who primarily run zone coverages, such as Cover 2 and Tampa 2, rely heavily on a 1-gap DL to put pressure on the QB while the LB's and DB's attempt to confuse the QB by mixing up and disquising coverages. If you can't pressure the QB, then a competant passer will carve up a zone defense. If you have a beast DL, then it's a great defense. Another characteristic is they give up yards, but tend to limit the big play if the DEF is well coached and disciplined.
More aggressive DEF's, like a Zone-Blitz, comes with the chance that the extra blitzer will give the pass-rush the edge and pressure the QB into a sack or bad pass. Although, you also take away a man in coverage and put more pressure on your DB's in coverage. If they get beat and the blitz doesn't get there, then you leave yourself open for a big play.
I thought the Tampa 2 was extremely effective against Florida's offense. The coverage confused Tebow, and the pass-rush was able to get to him. With that said, quality talent is needed to make the Cover 2/Tampa 2 DEF's successful, so by the time the injury bug started biting the effectiveness of the DEF started degrading. If executed well, though, a blitz defense would work. Kind've like what Muschamp ran when Auburn beat Florida a few years back. It'd sure be a helluva' lot more entertaining to watch at least.