Texas got stale under Mack Brown. After Muschamp left, the defense suffered greatly and the great coaches (HC, Coordinators and position) were all gone. Then Mack left. There are extra losses whenever a coach leaves and new coaches install a new system, as Strong has, from the ground up. The program will be much better and stronger for it in the end. Texas is still a bowl team and is on its way back up already.
Michigan and Texas are not nearly the same level at this point. Michigan has had a bunch of different coaches come in and be unable to right the ship. Again, each coach coming in with a new system yields extra losses due to changing schemes and target recruit attributes. Michigan doesn't recruit as well as Texas and doesn't have that strong local base of 5 star talent in HS. Michigan may never recover, although $8 million/yr will go a long way. Bring in Harbaugh and he likely installs a successful scheme on O and D and he is a big name that will help with recruiting. He's still in Michigan, though, and recruiting will be harder there than it would be in Texas or California. The good news at Michigan is that the B1G sucks and Michigan can elevate pretty quickly if everything else breaks right for them.