The usage rules as layed out in GAME INFO shoudl be read literally.
If no penalty is mentioned there is none.
Therefore:
1. Using a pitcher who is ready but not at maximum has no effect on his performance.
2. Uisng a starter at 21 (less than 30 BFA) can get you in a lot of trouble in terms of injury and lsot performance. This is talked about in Gamer Info in the usage section.

Mike Bravard
PB