Playing defense the way they are I don't see how they'd possibly lose 4 games the remainder of the season. I hate all things maize and blue, but generally the games that slip away or teams lose because they have no business losing are because the shots simply aren't falling for them or they decided to take a night off on the defensive end.
To play defense the way Michigan has been night in and night out takes a mental focus and is not something just any team can do. Playing that style of defense does two things (1) it allows easy baskets while limiting good looks by their opponent and (2) takes a great deal of pressure off them on the offensive side because they don't have to worry about trading baskets.
I hope I'm wrong, but where you see Michigan falling off and coming back to earth I see them continuing to get stronger. If they were in a position where they were winning games by simply out scoring teams I'd agree with you 100%, but I think Michigan is absolutely for real and going to continue to get better.