Football Outsiders has an interesting article outlining the three biggest factors in comeback or "turn around" seasons.
If you have ESPN Insider you can read the full article here.
FBO ranks three key categories as spurs for comeback seasons: Improved Health, Improvement at QB and Regression to Mean. According to FBO the Redskins fit all three categories.
Improved Health - The 'skins were one of the most injured teams last year. If they return to league averages they will grab this category.
Improvement at QB - McNabb has arrived with a sequoia sized chip on his shoulder
Regression to Mean - According to FBO most teams are .500 in games decided by a touchdown or less. Last year the 'skins were 2-7 in such games. If they move back to average that alone should pick up three wins. There is some additional data regarding point differentials that I'm too lazy to write about.
Football Outsiders is predicting a big improvement for the Redskins in 2010 to 9-7 and 2nd place in the NFC East. They're also predicting the Cowboys to be last in the NFC East. Both are reasons for hope for 'Skins fans.