In Chess, the standard metric is Elo, which weighs losses against "bad" players more heavily than losses against "good" players. Same for the opposite scenario (winning against bad players is not worth much, winning against good players is worth a lot).
Things like ERA, Batting Average, and On Base Percentage don't at all take into account the skill of the opponent. If a closing pitcher is most often pulled out against good batters, obviously his ERA will be worse than if he were to pitch against any random batter. Same for designated hitters, etc.
Is there not any Elo-like score in sabermetrics (baseball statistics) that accounts for opponent ability when adjusting for ones skill level?
Games like Chess, and even video games like Halo use Elo-like systems to assign scores to players. I was just wondering if Baseball did.