I know it's a bit late for a post, but I figured I might as well throw this out there for future reference.
There are some pretty good responses here. It is very important to listen to your body. But to do that, you must first learn how to do that. I played baseball through high school, college and at the pro level and have tried everything from lifting heavy, to not lifting at all. In the end (around junior year of college) I found that cutting back from 4-6 days of training to 2-3 days of shorter, but still high intensity sessions worked best.
But I am not you. What you should do is try out different methods while staying safe and paying as close attention to your body as possible.
Just remember, the farther you go with baseball, the more you play. And, while it's a very low-key, slow moving game, it will wear you down big time if your not careful.