They still have Cyrus Gray
Yes, but for the year they have been splitting carries, almost evenly combining for 33 carries a game. Now Gray will take on the bulk of the load and some other back (besides Tannehill and the QB run game) will have to take on some of it. (they have no other back that averages more than 1 carry a game) It changes what they do, especially when Gray is already banged up, its not like they are going to be able to give it to him 30 times. Plus, Michael is their big back (5-11, 215#) and I think he would've given our smaller LBs more trouble.
Don't get me wrong, aTm is good. Tannehill is a solid QB, Gray is a good back, and Swope is an explosive reciever. But this offense is not what we've seen the past two weeks; they are not even better than 5 of the Big 12 offenses we've already seen. Take out their best and biggest back and the guy who accounts for 46% of their rushing yards per game and I think it matters. Especially when aTm relies on running the ball much more than most (OU, OSU, TT, BU) of the teams we've already seen and had trouble with the pass against.
