I think is a stamina issue. I'm no expert but I don't lift weights i'm 5'10" and I can hit the ball out of the park in a big league park. I  played Baseball untill my 20 something.

So it's a good question that is why only think is a stamina Issue something to keep you going. In that way yes is cheating but the part that you can eve touch the ball a 95mph and hit it perfectly he deserves some credit