I think it depends on how old he is. If he is jr. high level, I don't think one season would hurt. After that he can alternate each year or work on what sport he needs more work on. I also agree that more than one sport is good. As far as Car Ripken and using diffrent muscles.......Okay I won't go there. Greco teaches you to use your hips, and freestyle teaches you to wrestle at a faster pace.