As a starting 5, I can buy this. But May, and particularly McCabe, do have value for this team off the bench. McCabe brings the kind of energy that is good for a team. He's a garbage man, and I think by the time he's done more people will appreciate what he brings to the team. Is he a Big Ten-quality starter? No. But he IS a Big Ten-quality role player off the bench.
The big reason McCabe currently starts, IMO, is because White also brings a lot of energy off the floor (as well as skill/production). It's a big boost to have a guy come off the bench who can go for 18 and 6.
The fact that White comes off the bench and routinely gets starter's minutes, seems to back this theory up (White had 27 minutes last night, McCabe 11 and he wasn't in deep foul trouble).