No doubt that Wentz is a significant improvement over the Qbs they had. Even if it only results in a 2 or 3 game improvement, that puts the Commies right in the playoff race.
The Washington running game is ok. It isn't as good as Indy's, but the Commie pass blocking rated out higher than the Colts'. So, it might balance out. He'll have Tmac to throw to and McKissic is a good pass-catching RB, Thomas is underrated at TE (though an upgrade is necessary).
The Washington FO was desperate for an upgrade at QB. They got one and didn't pay all that much for him in terms of draft picks.