It’s pretty common for kids to drop out of Baseball around that age. Baseball is a really really hard sport to play, if a kid doesn’t love it they won’t stick with it once they get to a level where it becomes really difficult.
I would tell him “this is a good opportunity to learn a life lesson, about commitment. You committed to this team, so we’re going to need to have you stick it out for the summer. You don’t need to keep playing Baseball after this summer, if you don’t want to, there are lots of things you could be great at. What are some other activities that might interest you? Let’s try to help you find ways to make this season fun. “