You can bet that with an Internet handle like "Year2", I've paid quite a bit of attention to the second year bumps that coaches tend to get. Bob Stoops, Mark Richt, Jim Tressel, Urban Meyer, and Nick Saban (at Alabama) are just a few of the examples of guys who had tremendous leaps between their first and second seasons.
Usually, the second year surges are a result of players getting more comfortable in new schemes. That will certainly be the case for Will Muschamp's defense this fall. He should get a boost from last year's very young team being another year older and bigger too. It also sounds like he'll get a boost simply by having a full staff of coaches all sharing his vision for the team.
This feature piece on Muschamp by Tony Barnhart talks a lot about the problems Florida faced in 2011. What sticks out to me is that it sounds like Muschamp made some rookie mistakes in building his first ever staff as a head coach. Muschamp says he likes the fact that new OC Brent Pease has coached in the SEC before, so he therefore "gets" the league and knows the week-in-and-week-out grind of the league. I think that's overblown given that the NFL grind Charlie Weis has endured is worse.
However, Weis brought in his own offensive line coach in Frank Verducci, and apparently Muschamp didn't like him at all. Verducci exited Florida in February to "pursue other interests", meaning he probably was fired. Tim Davis, the new OL coach, worked with Muschamp at the Miami Dolphins in '05 and according to the head coach is "more of my temperament as an offensive line coach". Muschamp even called Davis "the perfect fit" when he hired him. That's a fairly damning overall assessment of the guy who coached one of the weakest links of 2011's team. Notably, Verducci was out of coaching for a year when Weis brought him in, and he hasn't been hired as a coach again since leaving Gainesville.
Muschamp also replaced his strength coach Mickey Marotti after the latter left to reunite with Meyer at Ohio State. Choosing to retain Marotti was Muschamp's first move as head coach, but it sounds like it wasn't a good one. Marotti focuses on speed and quickness, much in line with Meyer's perpetual desire to have the fastest team in college football. Muschamp prefers a focus on size, strength, and explosive power, and not coincidentally, so does new strength coach Jeff Dillman.
Maybe those bad original hires were just rookie mistakes. Maybe they were due to executive meddling as Spencer thinks. Whatever the case, it sounds like Muschamp has a staff where everyone shares the same vision for the team. We'll see how much of a difference that makes for the team this fall, but it seems like the sort of thing that is a bare minimum requirement for competing in the SEC.