From Russell Carleton at Baseball Prospectus on September 6, 2018:
You can’t just randomly switch positions. Sure, you might have been playing a decent shortstop for the last few years. You might be a great athlete. But past experience tells us that you’ll probably be awful when you decamp to second or third base, at least initially. Eventually, you’ll get the hang of it, but that first month or so is going to be on-the-job training that will cost your team some runs. That might seem like an obvious statement, but it presents a large problem for WAR(P).
WAR is actually calculated in a way that assumes players can just move around, video-game style. The original idea behind replacement level was that if a team had been forced to play without a player (who actually did play), what could they expect in that alternate universe? The idea was that they’d pull someone in who played that same position. Of course, the new guy, who was a composite of players who weren’t “starters” during the season in question, wouldn’t be as good as a starter (otherwise, he’d probably be starting), but there was also an understanding that a backup first baseman would probably hit better than a backup shortstop, the same way that a starting first baseman tends to hit better than a starting shortstop.
Read the full article here: https://www.baseballprospectus.com/news/article/42505/baseball-therapy-the-under-appreciated-fielders/
Originally published: September 6, 2018. Last Updated: September 6, 2018.