I don't know, Eastmond was way ahead of the pack physically back then the way I remember it. He was skinny but tenacious as hell.
Maybe it really is as simple as him picking them based on training performances. I read a book about Arsenal a few years ago where people inside the club spoke about the way Wenger lets through youth in the first team. They said that if Wenger needs an extra player in training he walks over to the field where the reserve team is playing and asks for a player based on part personal judgment, part recommendation. If the guy does well he'll train with the first team on and off from that point, but if he doesn't look up for it Wenger won't pick him again.
Perhaps Coquelin just burnt a bridge early on while Eastmond looked eager to prove himself. Or maybe the reserve team coaches felt that Eastmond had performed really well and recommended him to Wenger as a way to spur him on.
