This concerns doing lineups that are LHP and RHP specific,
A) You are currently starting a guy who has good ratings against lefties and OK but nothing special against righties and he's never hit righties in his career to this point. He's destroying lefties, with an OPS that's been between .900 and 1.000 on the season, but in the same number of at bats against righties, his OPS is barely over .500. He has plus power against lefties too. Should he continue to be the starter against lefties?
B) You have a guy on the bench with good ratings against lefties and righties, essentially the same ratings, but he's for the most part an underachiever. He would never post an OPS anywhere near what player A does against lefties, but he would be able to do well enough against righties. He's a contact/slap hitter. Should he replace player A who can't hit righties.
C) The guy you are starting against the righties is posting a 1.000 OPS against them, but has weak ratings against lefties and did not hit LHP last couple of seasons. Should he be an everyday player?
Which scenario would you go with?