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Tuesday, December 09, 2008
Primer on: The need for the positional baseline
Someone asked me, so here’s my reply:
At it’s most basic, the question is: “How would Willie Bloomquist field at each position, relative to the average player already at that position?”
It presupposes that Willie Bloomquist is not predisposed to have a special skill that can be leveraged more by one position than the other. That is, he has average speed, average strength, average everything. It doesn’t have to be literally Willie, but any composite will do. Willie fits the definition so well.
Anyway, if Willie played SS, then the average SS would save 7.5 runs with the glove more than Willie would. If Willie played 1B, then the average 1B would save 12.5 runs less than Willie would.
The problem that we are trying to rectify is finding some common baseline to compare each of our fielder to. Since obviously the average SS is a far better fielder than the average 1B, we need to find a player who plays both positions, and is not a “natural” at either position. That’s Willie. I sometimes call this “Wins over Willie”.
With hitting, we don’t have that problem, because we know EXACTLY what the average hitter will do.
A question about the particular position adjustments you use—specifically, third base.
Your adjustment suggests that third basemen and second basemen are (generally speaking) equally talented fielders, and you can move a player from one position to the other with no significant change in their fielding value. But as a group, third basemen are much better hitters than second basemen. Doesn’t this indicate a longstanding misuse of resources on the part of baseball teams? Shouldn’t they be moving their third basemen to second en masse?
The same applies to the third-to-first shift, but in the opposite direction. The defensive improvement relative-to-peers when you move a third baseman to first outweighs the offensive decline relative-to-peers.