I looked at that play over and over, through the eyes of a fan and the eyes of an official. Typically, when the defender is progressing towards the runner without obstruction, the foul won't be called. So when the contact and grasp was made, the Bears defender was actually closer to the QB than the blocker was. This is obviously not the normal situation, because the blocker is usually between the runner and the defender. Anyway, in this situation, all the flailing of arms doesn't matter much; the official is looking for a jersey stretch or something similar. That's the only thing I can put out there for this no-call. It certainly looked like the defender was hindered while running towards Stafford, but I'm guessing they didn't see enough restriction since the Bears' player was moving towards Stafford.