For these attributes, it is easy for the coach to train all of the players on your team (he can have them shoot free throws for an hour or run laps around the building), and they dont depend too much on in-game practice. Therefore, selecting one of these options will train your entire roster, whether or not they play in any games that week.
Entire team would train. My fault. Guess I was mislead by the max training for other positions. Butttt who has 16 players anyway....:)