When you watch this from the end zone view, the B is moving to his position on the hash and appears to be looking at the area of the hit. I don't know about 7man mechanics, but in our 5man mechanics, the U, at the kick, moves toward the center of the field 1st assuring the safety of the kicker for 5 yds. then observing the center of the return teams formation checking for fouls by either team. I can only assume that the B & U split the field in 7man mechanics. I think that we sometimes get focused on holding, block in the back, and low blocks in the center on returns. In the not so distant past, this hit was viewed as O.K. and was not emphasized as dangerous. I think we as officials are definitely getting direction through the recent rules changes that these types of hit are not to be tolerated. I think it behooves us to put in more study so that we recognize this as automatically as we recognize a hold or block in the back.