Jack's dislike of exercise
Having just watched it again last night, there is something that has always bothered me about Jack Elliot. He laments being dumped by the majors, and when he goes to Japan he demonstrates how adverse he is to the very notion of an exercise plan.
While baseball tends to be less demanding physically than football or basketball, you still need strength to hit the ball and speed to run to a base.
As a major league baseball player and particularly for an aging one, you would definitely want some kind of overall physically training to help keep you as physically sharp as possible.
You need to stay in shape also to keep from tearing muscles say when you throw a ball very hard or when sliding into a base.
We see how devoted the Japanese players are to physical training, Jack does eventually adopt the same attitude and it does seem to help him greatly as a ballplayer.
He really should have had this attitude when he was in the majors before he went to Japan.
You may be a major league ballplayer who gets cut because you no longer seem to have it, but if you have keep yourself in shape then you would know that you did everything you could have to prevent it.