San Francisco has a historic season in 2011. They tied the NFL record for fewest giveaways, and piled up the 4th highest turnover differential (+28) since 1940. Few statistics have a higher correlation to wins than turnover differential, so it is worth looking into the chances that the 49ers could repeat the feat.
Here are the five teams that have posted at least a +28 turnover differential since 1940:
1983 Redskins +43
1958 Colts +30
1963 Bears +29
1960 Browns +28
2010 Patriots +28
2011 49ers +28
Each of the previous five teams to post a differential that high saw a drop the following season.
1983 Redskins -65%
1958 Colts -13%
1963 Bears -110%
1960 Browns -82%
2010 Patriots -39%
Three of the five teams saw their win total drop, the other two stayed steady:
1983 Redskins -3 wins
1958 Colts EVEN
1963 Bears -6 wins
1960 Browns EVEN
2010 Patriots -1 win
San Francisco will either become the first team in NFL history to repeat their level of turnover success, or will need to find other ways to win.