Backups: Ryan Moats, Lamar Gordon, Reno Mahe, Bruce Perry.
Westbrook is a versatile back who can cause match-up problems in the passing game when the defense tries to cover him with a safety or linebacker. He's a good perimeter runner, but isn't very effective between the tackles. Persistent fears about his durability were confirmed again when he went down with a foot injury late in the season.
Moats is a similar style runner to Westbrook. Gordon was inadequate as a short-yardage guy. Perry is not a very good blocking fullback. He can catch the ball out of the backfield, but doesn't have the speed to do much with it after the catch.
To make matters more interesting, Mahe is a restricted free agent and Gordon is an unrestricted free agent. The Eagles may let both of them go and look for replacements, possibly through the draft. However, it's unlikely that they'll go for a running back in the first round, so don't expect an impact back to come to the Eagles from the college ranks.
With all of that being said, the Eagles may look to add another established back to their roster during the off-season, as well. They may even look for a back who can work in tandem with Westbrook and give some insurance against another injury.
If you dare to dream, Edgerrin James said recently that he doesn't see himself returning to the Colts. Plus, Carolina's Deshaun Foster and Shaun Alexander of the Seahawks are also free agents. Dream away. Other names like Ron Dayne, Ahman Green and Antowain Smith are more likely.