Eh, what? They do.. Baseball economics however, plays a factor in that.
The notion that chemistry doesn't play a factor in a team sport that's played over a 6 month span and covers 162 games plus playoffs is laughable. Is it quantifiable? Not really, it's intangible, but it's there, and I've heard far too many people who know more about the game of baseball than anyone here comment on what a big factor it can play.