Pretty vague question, I'll try my best.

First off, what is your son's caliber in both sports. If he's just a recreational wrestler/baseball player, I'd say both.

If he's on an elite team for baseball and is just starting freestyle, I still say both. Freestyle starts in April and is done by May (competitively). Baseball usually starts in mid March and if you're on an elite team, they play every weekend. So the days he isn't playing, have him in the room. More than likely he'll chose freestyle next year because it is WAY less demanding than baseball elite teams. Heck, it's less demanding that folkstyle for that matter.

If he's an elite wrestler and elite baseballer, then your going to have to chose one or the other. Since it's his first year of freestyle, I say start him slow this year and let him figure it out for next year once the season is over.

One of the key things to remember is to make sure that whenever a season ends, he wants more and isn't excited about the season being done.