They don't have a heavy. They can't run around with Boston's players and get away with it. that's just where it stands. As for sticking up for each other, sure, that's a point of contention, but other than Erskine, they don't have a heavyweight. They don't even really have an enforcer. To be fair, Erskine's at the point in his career where he is too injury prone to be out there throwing each night. He isn't a day in and day out fighter. The organization might have something to do with it, but that's more of a "we don't have an enforcer" more than a "tone it down guys".
You can get guys playing with more snarl if they know they have a heavy on their roster. Guys like Hendricks/Chimera can't run around if they're going to have to pay the piper too often.