Reid scored his first goal in over two years from the penalty spot in Tuesday's 5-2 Carling Cup victory over Peterborough.
The midfielder's long-term future was questioned last week by Republic of Ireland coach Giovanni Trapattoni after missing almost two seasons with a serious knee injury.
Trapattoni's claims earned an angry rebuke from Rovers boss Sam Allardyce with Reid making his third start of the season in their win over Championship side Peterborough.
McDonald believes Reid still has a lot to offer and just needs a run of games to build up his fitness after such a long time out.
"When you have a major injury like Steven has it takes a long time to come back," McDonald told the Lancashire Evening Telegraph.
"He is the ultimate professional, he looks after himself and tries to do the right thing.
"It is frustrating when you get a few niggly injuries but he has kept going, kept his confidence up and a terrific performance capped off with a good goal.
"He will be a big asset for us when he is fully fit. I think he just needs games now. He has done all his strength work and core work.
"It is just his games and if gets a chance to play regularly I am sure he can contribute hugely the way we play."