Nope.
The only way to fatigue is by innings. You pay for innings in the draft center, you get innings. You'll get the same number of IP out of a pitcher if he pitches at safeco or coors (the quality of the innings may vary).
You think that there weren't a few very short IP out there in real life for the pitcher? You think that nearly every pitcher out there didn't have a few 35-40 PC innings during the course of a season? It's built into the IP. You get the IP you paid for, no 100's of free IP to stretch as you like by playing in Safeco, or with a good defense, or....