The blocking in the back is being stupid. These players have all been playing for several years. How many times do they have to hear "if you see the player's name on his jersey, don't touch him" before they get it? You see this called on many INTs, so I guess you can't be as hard on defensive players who aren't used to blocking but it's still the same instruction. There was that play in the 4th quarter when the replay showed that Foster hit the defender in the back but, not satisfied, he did it again harder to get the penalty. The Bills scored a TD on the next play so it didn't matter but these dumb penalties are usually costly. As you said, either these infractions are not being emphasized enough in practice or the players are stupid.