They need to have like in the Japanese Baseball Spirits game player performance carryover and fatigue carryover game to game...
Ideally if you have someone who is say 1/4, 0/3, 0/5, in a series , ideally theyll play cold and colder, wont get on base, have a harder time getting on base and even fielding. Though those who are raking going 3/4, 2/4, 3/3 ETC will play better offensive and defense as well. Same for pitchers, but stamina is also a factor, making sure someone is rested a full 5day or more and not using bullpen guys over wheat they can throw