I played D1 baseball, but didn't really think about going to medical school until some point during my 4th year (I took 5 total, change of majors, red-shirted, slacked off, etc) so I'm not 100% qualified to answer this. It will be hard, but it is doable, and baseball is pretty much year-round at the D1 level. There were 2 other guys on the team who both wanted to go to medical school and got very good grades as science majors (>3.5) while being starters. Of course, they both eventually changed their minds,one's in optometry school and one getting a Ph.D., but that's beside the point. I managed decent grades my whole career and I think had I actually known early that I wanted to go to medical school I could have got grades in the 3.6+ range. What it will take is great time management skills and supreme devotion both to your sport and to your goal of getting into medical school.
I would also plan on not being able to apply during your senior year. I don't think you'll want to be filling out aps, competing, and studying for the MCAT, and trying to interview all at the same time. I would recommend an elongated application process, probably with 1-2 years off after school to build up ECs, especially shadowing and take the MCAT. Otherwise you might overload your plate during your time in school.