I'm not sure exactly what you're looking for, but for SP, you want your guys to be back to 100% on 4 days rest (for a 5 man rotation). Some say 100% = 100%, so make sure your best pitcher is on the hill every time he's back to 100%. Others say there is a benefit to having your pitcher be at 100% one cycle prior to his start.
The amount of "rest" they will gain each cycle is roughly their durability rating (25 durability will gain back about 23 percentage points in fatigue each cycle). So I'll bump up the pitch count if he's got a 35 durability rating compared to someone with an 15 rating (for which I might knock down the pitch count a bit).
Is this what you're looking for? If not, please be more specific.