That's an odd example since more than a few folks would argue the latter, that diarra will be starting over mahaney...in fact there's a pretty solid chance they're starting alongside each other
Diarra will get a ton of minutes, whether or not he is the starter. I have no idea what to expect from Mahaney, Diarra is a tough player to beat out, but someone just listed Mahaney as a sleeper All-American, and I can't see Diarra being considered for All-American status.
They could both be starters, but then you'd have to sit one of McNeeley or Stewart, and I consider both of those as guys who have to see the court.
For my money it's probably Mahaney-Diarra-Stewart-McNeeley getting the bulk of the minutes at guard and wing, and Ball, Nowell, Abraham, Ross having limited minutes.