Vargas probably isn't as good as he was in the first half nor as bad as he's been in the second half. Goes for Estrada and a lot of guys. Heck, it went for Pomeranz last year.
The real point is that people need to get off this should have pounded him crap based on their perception of stuff. There are many ways to get hitters out, not all of them involve throwing the ball 95+. Maybe the Sox hitters just aren't as good as people here think they are.