We touched on this in an interview with Aaron Schatz of Football Outsiders this morning, but it's worth fleshing out a bit in a separate post: just what can we expect, scheme-wise, from Buffalo Bills defensive coordinator Mike Pettine this season? FO's metrics can supply more specifics beyond the still-very-true keywords of "multiple" and "hybrid".

Essentially, you can expect to see the exact opposite of what the Dave Wannstedt defense looked like a year ago for the Bills, in many key respects. Let's crunch FO's numbers, starting with the percentage of time that the Bills spent in specific defensive personnel groupings, as compared to the 2012 New York Jets:

Personnel BUF '12 NYJ '12 4 DB ("base") 44% 39% 5 DB ("nickel") 41% 39% 6+ DB ("dime") 10% 17% (miscellaneous) 2% 5%

This basic look at general packages - base, nickel and dime, which differ only in the number of defensive backs on the field - doesn't show radical differences between the two teams. The Jets were clearly more comfortable relying on their dime defense than the Bills were, which likely ties into the fact that the Jets were much better against the run than the Bills were last year. Aside from that, there isn't much to write home about here - but we're only just getting started.

Personnel BUF '12 NYJ '12 4-3-4 base 40% 14% 3-4-4 base 4% 25%

Split up the teams' respective base personnel percentages, and you begin to see the differences. When the Bills went with four defensive backs last season, they were overwhelmingly in a 4-3 front. The Jets, likewise, used the 3-4 as their base, but note that unlike the Bills' occasional use of the 3-4, the Jets used their 4-3 as much more than a unique, once-in-a-blue-moon option. While most NFL teams skewed heavily towards one base defense, the Jets were one of three teams to use each base on at least that many snaps (New England was 25-15 in favor of a 3-4, while Indianapolis was also in favor of a 3-4 by a 39-18 margin).

The entire point of the Bills finding edge players like Mario Williams, Manny Lawson and Jerry Hughes? They're all players that can stand up in a 3-4 or put their hand in the dirt and turn it into a 4-3 on a whim. You can fully expect to see a similar split between base fronts for the Bills under Pettine in 2013.

Personnel BUF '12 NYJ '12 Even front 33% 23% Odd front 11% 16%

The above chart breaks down each team's nickel figures, splitting them between even-front (such as a 4-2-5) or an odd-front (such as a 3-3-5) look with five defensive backs. Again, you can see that the Jets were much more willing to more evenly split their nickel time between different looks, while the Bills (like most NFL teams) were content to use a 4-2-5 nickel 75 percent of the time they used that personnel grouping.

Personnel BUF '12 NYJ '12 3-4 base 4% 25% Nickel (even) 33% 23% Dime+ 10% 17% Nickel (odd) 11% 16% 4-3 base 40% 14% (miscellaneous) 2% 5%

Here's the full breakdown. The clear and obvious difference: the Jets made a much more concerted effort to spend time in several different looks, even as they were essentially matching up with offenses, personnel-wise, that all NFL teams do. We knew all of this coming in, but the FO numbers could give us a better idea of what to expect as Pettine switches up defensive fronts in 2013 with his new team.