From Russell Carleton at Baseball Prospectus on February 10, 2016:
I’m guessing that many of the people reading this will have come to appreciate the game of baseball the way I did, through the magic of baseball cards. When I was growing up, a baseball card told you three things on the front of the card: the player’s name, the player’s team, and the position that he played. It’s something that’s deeply ingrained in how we understand baseball. Players have their positions. And we know all nine of them. Well, of course, there were the utility infielders. I remember when I was 7 that I called them “switch-position” guys. They got little dashes in the little circle where it showed their position. SS-2B. 3B-1B. In baseball, it’s perfectly legal to shift around the park, but the good players, they had a regular spot to hang out in.
Now that I’m older, I can appreciate the importance that the position that a player holds down has in terms of determining his value. The idea of the defensive spectrum is something that’s been around since Bill James introduced it in the 1980s. James initially conceptualized the defensive spectrum by noting that there were several shortstops in baseball who held down regular jobs despite being awful hitters. There were no first basemen who could make the same claim. James lined up the positions in terms of their average production and found that it neatly aligned with the accepted wisdom of which positions were toughest and easiest to play. Center fielders and shortstops were allowed to get away with .230 batting averages because those spots are the hardest to play. If a first baseman tried to hit like that, he wouldn’t be a big leaguer much longer.
When we try to figure the “true” value of a player, we have to take into account his position, but how we do that is a little tricky. The most common way—at least when putting together uber-metrics like WAR—has been to use a positional adjustment to give a player credit for playing a more difficult position (or penalize him for playing an easier one). Smith might not hit very much, but the fact that he can play a competent shortstop means that third base wasn’t clogged up and his team is more likely to find someone who can hit if it dips into the third base bin rather than scrounge in the shortstop bin.
Read the full article here: http://www.baseballprospectus.com/article.php?articleid=28408
Originally published: February 10, 2016. Last Updated: February 10, 2016.