Football Outsiders has tracked 20-yard runs and passes over the past five seasons. Not surprisingly, winning teams tend to give up fewer explosive plays than losing teams. But the correlation between winning and preventing explosive plays is not as stark as the correlation between winning and creating explosive plays. And neither is as stark as the correlation between winning and explosive play differential.
On the other side, the Browns have averaged the worst explosive play differential (-19.8), followed by the Bills (-15), Rams (-12), Raiders (-10.2) and Lions (-8).
This is the reason why the Rams have drafted and signed players with game breaking ability in the offense (Sam Bradford, Mardy Gilyard) and the ability to tackle in the secondary (Jerome Murphy, Kevin Payne).
Plain and simple, teams that create explosive plays are much more likely to win the game and the Rams have failed at creating explosive plays on offense in 2009. They also were subject to giving up big plays on defense as well. Both need to be remedied for the Rams to have a successful season in 2010, but at least it look like the Rams are addressing their deficiencies.