First, the whole bullpen AI in OOTP 14 is basically brand new. It does a better job managing the bullpen.
Second, you can increase roster sizes and force the AI to carry X relief pitchers in OOTP 14 (league strategy settings), so that would take care of tired bullpens. The default setting for DH leagues has been tweaked too, modern leagues carry now 7 relief pitchers instead of 6.
So, give OOTP 14 a try, I bet you'll like what you see
