THE BOOK--Playing The Percentages In Baseball

Tuesday, November 02, 2010

“Can someone explain [blank] to me?”

Someone asked about FIP and WAR.  My reply:

FIP is fielding-independent pitching.  What the stat does is focus on a subset of pitching, and that subset is that which does not involve his fielders, and does not depend on the order of the events allowed. 

This would be similar in analogy of OBP focusing on a subset of hitting (getting on base, treating a walk = HR).

The weights of FIP are not arbitrary, but reflect the impact those events have on run scoring.

FIP = [13*HR + 3*(BB-IBB+HBP) - 2*SO] / IP + 3.20

That 3.20 changes for each league/year, and is set so that the league FIP matches the league ERA.

***

WAR is wins above replacement, or as I sometimes call it W/W, Wins Over Willie (Bloomquist).  That is, how many wins did this player contribute, over and above what you’d expect from Willie Bloomquist playing that player’s position.  (For starting pitchers, I don’t have a good example, but I go with Kevin Jarvis.  For relievers, well, take your pick: the league is filled with them.  These are just faces to give to the idea of a replacement-level player.)

Anyway, each event has a certain impact to scoring runs (and winning).  Those events are weighted, and various adjustments are applied (position, park, playing time, etc).  It tries to capture the totality of a player’s contributions into one number.  That number is not fixed in stone, but has a certain level of uncertainty.

Why do it all?  Well, because it makes it easier to discuss if we all use a common framework.  And, how many games do we watch?  There are 2430 regular season games in the league.  This is why we count hits and walks and home runs.  That’s why we aggregate it at the player level.

So, we try to aggregate it even more, so that it makes it easier to look for players, not only this year, but past years.

This process has tremendous value to front offices and to a certain segment of baseball fans.

If this is not your party, that doesn’t mean it’s not a good party.  It’s just not your kind of party.  Think of baseball like Manhattan, and that FIP and WAR can be found in Hell’s Kitchen.  If you prefer the Village or Central Park, no one is stopping you, nor dismissing your choice.