The winger has shown flashes of brilliance as McCoist's side have claimed the Third Division and League One crowns but injuries have too often prevented him showcasing his full talents.
An ankle knock picked up at Annan two years ago was the start of a troublesome spell for Templeton as he has struggled to hold down a regular starting berth.
But boss McCoist is confident he can show what he is made of in the Championship after turning the Petrofac Training Cup tie against Hibernian in midweek in Rangers' favour.
He said: "I think he's got to be a big player for us this year. We all know the talent he's got, he's got gifts that no one else probably in the division has got. But the only person that can bring them out is David. It's a big year for him and he's hoping for big things, as are we of him.
"Well, you've got to cut him some slack with the injuries. It goes all the way back to Annan a couple of seasons ago right at the start of his career here, so I wouldn't be overly critical of him because he's definitely had problems which are outwith his control.
"But all we can hope for, David included, is a clean bill of health and an opportunity for him to play and express himself. Because when he plays and is on form, he'd be in most teams."