encouraging a child to play a sport in which he is burned out

My 12 year old son has played both baseball and basketball since he was very young. He is naturally athletic, and has always excelled in both sports. In the last 2 years or so, however, even though he is one of the best players on the baseball team, he seems to be losing interest in the game. His being such a good athlete causes all of the coaches to pursue him for all of the extra leagues possible, little league, all star team, fall league, etc. He tends to enjoy the first of the season, but then he gets tired of it. He has the possibility of playing for his high school JV team--even though he is just in 7th grade, but he doesn't think he really wants to. Should I encourage him to try out? Or, would it be best to let him sit this one out? I wouldn't force him to play--but I'm wondering if I should encourage him to take this opportunity? It seems like such a waste of talent, but I don't want him to quit altogether.