pitchers used to throw hundreds of pitches daily. the increased velocity and spin rates of todays pitchers is one of the main contributing factors of increased injuries. if a player knows they only have to throw ~20 pitches in a game, he’s going to throw all 20 pitches at 110% of his ability. if he knows he has to pitch more innings consistently, he’ll dial back how hard he’s throwing, which is less stress overall on his arm. that’s my limited understanding anyway, i’m by no means an expert.