Snyder: Backups' success challenges U-M football starters

Freep writer Mark Snyder breaks down Michigan's 28-7 win over UNLV. Mark Snyder, Detroit Free Press

Harbaugh doesn't want to talk about any controversies at other positions ... besides QB, that is

(Photo: Julian H. Gonzalez DFP)As soon as Jim Harbaugh heard the question, he halted.

After two weeks with De'Veon Smith as the definitive No. 1 tailback, is Ty Isaac now in the mix to challenge him?

"We don't ever talk about any type of running back controversy," he said, closing his news conference after Michigan's 28-7 win over UNLV on Saturday. "Quarterback controversy, I'll address that. Whenever you want to know who the starting quarterback is, I will talk to you about that. But when it comes to…