Ladell Betts may miss more time that we originally thought.
According to Jason LaCanfora, Betts came very close to suffering a season-ending knee injury last Sunday and that he may not be back until after the bye week.
If that's the case, it makes sense of the Redskins' decision to bring in Shaun Alexander for a talk and a physical. Even if Jim Zorn is good with Rock Cartwright getting half a dozen or so carries a game—and I don't think that he is—you don't want to go with just two healthy running backs on the roster.
LaCanfora also says that it's not a lock that the additional back is Alexander. Some in the organization are making a case that Marcus Mason should be signed off of the Ravens' practice squad.
However, he was released despite leading the league in rushing in the preseason because he was having trouble picking up the details of the offense. As he has spend the last six weeks learning the Baltimore scheme, one would have to be skeptical of his ability to pick up the Washington offense in time to make a contribution.