Galen Rupp will be 26 in May and he has peaked. He will not improve any more, at least at the distances he has already competed in. His career bests will be 13:06, 26:48 and whatever he can eventually run in a marathon, perhaps 2:06 or so. Congratulations on a fine career, and of course he is not done, as he will continue at a fairly high level if he stays healthy.