I have to say, you can't merely look at how Marshall ran against OSU and then go to conclude that OSU will be in trouble against a quality back like McLendon (assuming he's 100%)
Marshall brings a completely different set of athletes and schemes than does NCSU. I remember times when very bad running teams ran all over OSU (back when the "spread" was a new thing) It's a personnel issue. It's a scheme issue. But it's not "No Name" Bradshaw put up X amount of yards, so McLendon will roll.
You also can't look at how OSU's D was unable to put up the defensive numbers Troy did. I wouldn't have expected them to. Using this "Hey, Troy did such and such, so we should be able to do even better" analysis results in things like East Nobody State being 7 steps from Kevin Bacon (and the national title). I don't buy it.
I've noticed that "smaller" teams tend to move the ball pretty well against OSU. I think this is because OSU is designed to face big teams with speed - since this is the formula that wins championships. Big speed beats little speed. Not really explaining that well, I guess. All I'm driving at, is these little guys run between OSU's legs in cartoonish fashion.