I don't think it's a big problem, but I do think it's a lack of size at a certain nose-tackle position.
As far as our run game, I can see several issues, like that right side I'm not supposed to talk about (which is actually MUCH improved in pass-blocking), but I don't see it being a problem with Foster. Some of it seems to be run-blocking; some of it is Tate--he's good sometimes and bad at others. Maybe Tate needs to be a Vegan.
Maybe Tate and Cody both need to be Vegans.