I believe that it is poor scheme and execution on 3rd-and-long. I don't ever remember a UM team that is this poor in zone coverage. I think the coaches may be snake bit by the big plays and are playing zone to limit them. Well, yielding several 3rd downs can be just as deflating as giving up a big play. At this point, on obvious passing 3rd downs I would prefer the DBs to be Trent/Warren/Cissoko/Harrison all in man coverage, 1 safety deep, and blitz the other 6. It is sad when the only time you feel like you can get a stop on 3rd-and-long is w/ a sack.
I thought that myself when I read that article that talked about a Data Scientist(tm)