Kiffin is adding an interesting wrinkle to the Bucs defense by introducing a 3-4 defense to be used intermittingly with the base 4-3/Tampa Two. For the details on how the 3-4 would work check out BucStats, which has just been the bees knees lately.
This is the first time, since Kiffin took over a decade ago, that I can remember the Bucs planning on using the 3-4. But considering this is a copy cat league, and the 3-4 has been the soup du jour lately it makes sense to add it. While I doubt the 3-4 will do much to improve the Bucs rushing defense (they lack the over sized linebackers to man the middle), it should help improve their dreadful pass rush. I criticized the Bucs for adding too many linebackers at the expense of not adding enough lineman before, so adding a 3-4 certainly fits the Bucs talent to an extent. In fact I wouldn't be too surprised to see the Bucs use the 3-4 almost exclusively in passing downs to give opposing quarterbacks a different look.
What's more interesting to me is that Kiffin has enough faith in his defense to add an entirely new formation. With a large influx of new players and an entirely new set of defensive coaches it speaks highly of the new guys that Kiffin is willing to introduce something new. Kiffin has never been a guy to shy away from experimentation, but the players typically have to earn his respect before Kiffin will use something different come gameday. It seems like so long ago now, but it was just a few years ago that Kiffin would not shy away from dropping Sapp or Rice into pass coverage and blitz Ronde off the edge.
Additionally, I wonder if Kiffin has been talking to his former protege in Pittsburgh, Mike Tomlin, who is now in the process of merging the Tampa Two and 3-4 defenses? The Bucs don't play the Steelers for another four years (unless they meet in the Super Bowl) so there's little reason why the two would not be willing to help each other. Perhaps the two coaches could devise a defense combining the best elements of the Tampa Two and the 3-4?