MacIntyre has been injured his whole career, which is why he hasn't established himself in the Wings' pipeline. Last season he was healthy and had a good year in the ECHL, and had a few good games in the AHL playoffs.
The truth is nobody knows how good he is. It's pretty certain that he's not an NHL starter caliber guy, but he might be a decent backup someday. I wouldn't bet on it with his history of injuries, and the fact that he has very little experience above the ECHL level. But we'll see.