So the problem is he isn't getting taller or he isn't getting any muscle from working out? Unless its some crazy muscular deficiency thing that makes him frail then sure. I mean speed is still a thing in sports too. You don't really need to power through people all the time.

Correct especially considering the postion his playing he just needs to get the ball in right space if you look at south africa springbok player faf de klerk he is small but he can kick and pass at the correct time.