If Mike Shanahan is serious about evaluating his players, then he'll bench Casey Rabach and let Will Montgomery start at center. Montgomery might not be the answer, but Rabach has been overmatched in almost every game this season. He's a great individual, but his best days are long gone and Montgomery has been solid when he does play the position (e.g. vs. Tennessee) Plus, a matchup against Jay Ratliff, who normally dominates the Redskins, would tell us a lot about the Virginia Tech grad.
The Redskins have to win the battle up front to control the ball on the ground. Ryan Torain's punishing style can energize a team and he will be hungry to build off a tremendous performance last week. If the Redskins can generate a push, Torain will have a big day and Rex Grossman won't be throwing 50 times.
Should Grossman have to air it out early and often, you can scrap this game. The Cowboys pass rush will tee off on a quarterback who really isn't all that talented. He might put up yards, but he'll also contribute a few picks. The main point of interest will be how the playcalling changes with Grossman under center, and also whether or not the top weapons, primarily Chris Cooley, are targeted more frequently.