Craig Levein's Scotland team kicked off qualifying with two home draws against Serbia (0-0) and Macedonia (1-1) earlier this month but former Rangers and Aston Villa boss McLeish feels that Brown and Fletcher are the keys to getting things back on track.
"I know Craig's gutted and all the fans are at getting only two points from the first two games. But it's in the past now," he told SunSport.
"The players respect Craig and seem to want to play for him, now they need a bit of inspiration in two hard away games.
"Getting Darren Fletcher and Scottie Brown back will give us a bit of impetus.
"Boys who play at their tempo would definitely help us.
"There's some good talent in the squad, they just didn't show it in these two games as much as we would all have liked.
"We took those two home games for one reason and that was to get off to a flyer in the group. It didn't happen, but I don't think all is lost."
Brown missed the Hampden double header due to an ankle injury whilst Fletcher has not played for his country since last year because of a chronic bowel problem, however, both players are due back in Levein's squad for the October 12 trip to Wales.