While Banta-Cain racked up a couple of sacks, I wouldn't be so quick to say that he was playing well. I don't have access to the game film but he has only made 13 tackles all year with 3 being sacks. What that tells me is that other than the pass rush, he isn't doing a whole lot.
He could be missing his coverage assignments, tackling poorly, not playing the run well, not following the line of scrimmage checks from the middle linebacker...just a whole host of things. We as fans see 3 sacks, a very glorified tackle and think he's playing well but could be missing all the bad other stuff that got him cut from San Francisco and now New England.
In Bill I trust!!!