San Francisco 49ers' defensive coordinator Vic Fangio is widely regarded as one of the top defensive minds in the game of football. 49ers' head coach Jim Harbaugh wisely focuses on the offense and allows Fangio complete reign over the defense.
This approach worked brilliantly in 2011. The 49ers' defense was ranked second in the league in terms of fewest points allowed. They gave up an average of only 14.3 points-per-game.
In addition, the 49ers' defense was the best in the NFL against the run. They allowed only 77.3 yards-per-game rushing.
The 49ers return all 11 starters from last years' squad. The only change will be that Aldon Smith will become the starter at one outside linebacker spot and push Parys Haralson to the bench. Smith collected 14 sacks in 2011, in a part-time role.
The 49ers will again be very strong on defense and frankly, I do not expect to see any major new wrinkles on the defensive side of the ball. Fangio will simply work to improve on the things the 49ers already do on defense.
The only real modification I expect to see is more rest for the front three down linemen. The trio of Justin Smith, Isaac Sopoaga and Ray McDonald played nearly every defensive snap of every game.
McDonald and Sopoaga started and played in 15 of the 16 regular season games. Defensive end Justin Smith started and played in every single game. These three stayed healthy over the course of the season, but that is unlikely to happen for two consecutive years.
Reserve defensive linemen Demarcus Dobbs, Ian Williams, Ricky Jean-Francois and Will Tukuafu should see more playing time. This will help keep the starters fresher over the course of a game and for the entire season.
The only other thing I see as something Fangio might alter are the blitz packages. If he sees teams stepping up to double-team Aldon Smith and stop him from getting to the quarterback, Fangio could drop Smith back into coverage and send some unexpected blitzes.
One thing about Fangio and his blitz packages is that he will vary where the pressure is coming from. One time, it may be the opposite side with Ahmad Brooks, or perhaps up the middle with NaVorro Bowman or Patrick Willis.
We could also see more safety blitzes from Donte Whitner or even corner blitzes from Tarell Brown or Carlos Rogers. Even with some of these more unpredictable looks, the 49ers are not likely to make any major changes to their defensive scheme.
The bottom line is, "if it ain't broke, don't fix it." With everyone returning to an already very strong defense, this unit is again poised to help lead the 49ers to a Super Bowl.