The very geeky Letsrun.com has a fascinating article with links to the long, long pre race statistical odds of Meb or Ryan Hall winning, somewhere between 0.05% and 3.7% with 14 runners, including Ryan Hall with personal bests better than Meb's. Yet Meb has proven over and over, despite his "age" that he is willy focused racer on the big day.
Essentially Meb, assisted by fellow American Josphat Boit at the front ran his own race and own pace. The Africans in a pack behind ran as if nothing was to be worried about, Meb would fade. They sped up, slowed down dramatically but never tried to close the gap, figuring Meb would fade. Realizing what was going on, and Meb had a chance to stay away, Ryan Hall organized his fellow Americans telling them if they maintained the steady pace they wanted to the Africans would respond, and the chase would be on. On the fly they decided Meb was the best chance for an American to win.