Allen is more mobile than Haskins, but he is a career back-up who has had limited success.
He is not as good as the Dak, Wentz, Josh Allen or even Daniel Jones.
The issue for the Rams probably won't be defending the Washington O, but rather the Rams getting back on track with their own O and handling a very good Washington front 4. As McVay said this past week (and Goff echoed), the issue was execution. For whatever reason the Rams usually seem pretty focused on the road. I fully expect them to bounce back with a better performance than last Sunday and to come home with a win.