THE BOOK--Playing The Percentages In Baseball

Thursday, September 23, 2010

Felix Game Score

Felix had an interesting game.  “He” lost by giving up one run (HR), walking 4, with 5 K, and a single.  He had groundouts coming out of his butt, including 2 DP.  It was a complete game, 109 pitches. 

I introduced 4 Game Scores the other day.  Yeah, I know, 4?  Like, how can the saber market handle 4, all coming from the same guy?  Anyway, they are all well-constructed, and focusing on particular aspects of pitching.  The first one was simply based on runs and innings:
GameScore = 6.7 * IP - 10 * R + 40

Felix had 8 IP, 1 R, giving him a GameScore of 84.  Basically, if he always gives up 1 run in 8 innings, he’ll win 84% of the time.  It’s actually closer to 90% of the time, but this is a crude metric as most linear metrics are, and they’ll break at the extremes.

The second one was based on K, BB, and IP:
GameScore = 0.5 * IP + 3 * (SO-BB) + 40

That gives Felix a Game Score of 47.  Basically, focusing only on these stats, he pitched an average game.

The third one was based on the FIP categories:
GameScore = 2.7 * IP - 13 * HR - 3 * BB + 2 * SO + 40

That’s also 47.  Again, an average start.

The last one focuses on all the outcomes (H, HR, BB) and IP:
GameScore = 8.6 * IP - 5 * H - 8 * HR - 3 * BB + 40

That’s a Game Score of 79.  We’d expect him to win 79% of these games.  That sounds about right.  If you type in his batting line in my Markov calculator, which presumes random sequencing (but no outs on base, meaning no extra benefit from all his GB and possible DP), he should have allowed two runs.  And 4.5 runs scored of support against 2 runs allowed, using pythagenpat gives us a win% of 80%.

So, based on how you want to view Felix’s performance, this is his game scores:
84 - looking at runs allowed (includes sequencing)
79 - looking at batting outcomes (no sequencing)
47 - looking at FIP components
47 - looking at K, BB

We can discuss how much we should weight each number, but, basically, let’s say we do what I said in that thread:

For a single start, I would do 35% version 2 (K, BB), 30% version 3 (FIP), 20% version 4 (component runs), and 15% version 1 (runs allowed).

That gives us a Game Score of 59. 

A simple average of the above 4 is 64.  The simple average looks like this:
GameScore
= 40
+ 4.5 * IP
+ 1 * SO
- 1 * H
- 2 * BB
- 2 * R
- 5 * HR

Anyway, you need to play around with a few of these extreme games to see the resulting game scores and decide the right balance for you.  If we can come to an agreement, all the better.