The Designated Hitter—home of the offensively talented and the defensively challenged players. By not having to play the field many players have been able to prolong, or even make, a career through offensive contributions alone.
American League teams use the DH position for a variety of different reasons: from protecting a player’s health to finding a role for an aging player and everything in between. Despite the variety of reasons a particular player is used as a DH most of these players have a common trait—they can all hit but, usually, they are also a major liability in the field.
Unfortunately, NL teams are not afforded this luxury; since there is no DH in the National League every player in the lineup must be on the field (so instead of a DH, who takes the place of the pitcher, in the NL, the pitcher must hit for himself). Because of this, NL teams must be more judicious in deciding which players to carry on their 25-man roster.
Even if a player can undoubtedly contribute offensively he may not make a NL team because he will either not get many at bats (if he is used solely a pinch-hitter so to avoid him playing the field) or he becomes a major weakness in a team’s defense (if he is put in the field—either as a starter or to play more than a few innings…Pat Burrell started for the Giants in 2010 but when the Giants had a lead past the sixth inning Burrell would usually be pulled from the game for a defensive upgrade).
While some NL teams opt to have these type of players on their roster (Prince Fielder of the Brewers and Pat Burrell of the Giants, for example) most of these type of players are found in the American League.
To help us look at fielding abilities, I use the sabermetric stat of Range Factor Per Nine Innings (I use this stat, rather than Range Factor Per Games so playing nine innings versus playing one inning is waited more equal).
Let’s take a look at some American League players who could not, and should not, play for a National League team because their poor defensive would hurt the team more than their offense would help.