Saturday, January 20, 2007

The Did Your Job Stat(DYJS)

Baseball is a game immersed in statistics, moreso than any other sport. A diehard football fan would be hard pressed to name his quarterback's completion percentage or even be aware of how a Quarterback rating is calculated. When Rex Grossman has a QB rating of 0.0, we all know that it's bad, but we have very little idea on how it's calculated. Basketball only really has ppg, free throw percentage, and field goal percentage as far as casual stats go. Other stats exist of course, but even the well known stats aren't regular topics of conversation outside of Shaq's abysmal free throw percentage.

Baseball on the other hand is a completely different animal. Pitch counts are religiously followed by broadcasters with 100 being the magic number for when a pitcher is "done". If he throws 75 pitches he was underworked, 150 and the manager is going to kill his arm. A .300 batting average is the gateway between a good season and a great season at the plate. If you Win 19 games as a pitcher you had a good season, but if you win 20 games in a season people will refer to you as a 20 Game Winner for the rest of your life. Win 300 games in your career and you're automatically in the Hall but 288, not so much.

Even casual fans are aware of BA, OBP, ERA, Slugging, Wins/Losses, and OPS. More hardcore fans know such stats as BB:K, fielding percentage, groundball/flyball percentage, etc. Beyond this there are numerous more derivative statistics such as Win Shares and VORP.

Stats can be used to compare hitters to hitters and pitchers to pitchers, but there's no easily understandable stat to compare hitters and pitchers. VORP and Win Shares can be used but you practically need a phD in math to understand them, making them far outside the grasp of the actual fan. Enter the Did Your Job Stat(DYJS).

DYJS represents the percentage of the time that a player made enough of a contribution to help his team win. In any game that a player participates in he either Did His Job, or He Didn't.

A hitter can do his job by getting 2 Job Points in a 9-inning game. Job points are awarded as follows.
+1 getting on base safely
+1 getting a RBI
-1 commit an error
-.5 grounding into a double play
+.5 successful sac bunt
+.5 successful steal
-.5 unsuccessful steal

So, if you hit a homerun you did your job for the game since you "got on base" and got an RBI. Under this system, hits and walks are obviously equivalent if the bases are empty. If a player commits 2 errors in a game, he has severely hurt his team on defense and needs to have an outstanding day at the plate in order to make up for it. A pinch hitter or sub does his job if he has .5 or more Job points.

The metric for a starting pitcher is inspired by the idea of a quality start. Wins and losses are too arbitrary to truly measure a pitcher's performance. Only 2 things matter for an AL pitcher in whether he did his job, Earned Runs and Innings pitched. For every inning beyond the 6th, the pitcher is allowed an extra half-run, rounded down. So, he can't Do His Job if he allows 4 runs unless he completes the 8th inning. A NL pitcher can further help his cause by getting on base or getting a RBI and will be allowed to give up an extra .5 runs(rounded down). So, when Dontrelle Willis hits a grand slam(like he did against the Mets last year), it allowed him to give up an extra 2.5 runs in order to do his job. As far as grounding into double plays/bunting, this is considered normal for a pitcher either way.

This leads to the question about relievers. A reliever can do his job if he allows no runs if he has less than 2 IP. This includes inherited runners, because the job of a reliever is to get out of the inning, regardless of the situation he is put in. Relievers, in general, aren't as skilled as starters, so if they get extended work they're allowed to give up a run sooner than a starter. Closers are treated the exact same way as other relievers. Saves are nice for the stat book, but giving up 2 runs in a single inning is not a good thing regardless of the result.

I cannot say for sure without actually running some numbers if this will produce DYJS averages for good batters and good pitchers, but that's the idea. If it does not, I'll either have to re-tune the numbers or accept the idea that hitter and pitcher consistency cannot be compared. Good players should contribute to their teams success consistently.

The really cool thing about the concept of DYJS is that it can be applied to anything. Think of it as a Statistic Interface that can be implemented by anyone familiar with an activity. Take my job for instance. There are way too many kinds of tasks for me to give a score to, but as a sample, lets say I need to get 2.5 DYJS points to do my job for the day(and yes I realize that only me and perhaps Jeff have any idea what I'm talking about).
+1 fix a bug(on average anyway. some are more complex than others)
+1 full deployment to QA
+.5 push rules to QA
-.25 forget to turn on Rule debug after giving new code to Dev environment
+.25 fix a minor problem for someone(point out the "user error")
-1 a program that I maintain breaks and it takes me longer than 10 minutes to fix it, and it's caused by something being wrong in it initially and not the environment changing

For someone like a surgeon, he'd probably need 1 DYJS point to do his job and it'd look something like this.
+1 show up to work
-1 screw up

Using this metric, you could certainly compare a surgeon to a middle reliever, although I'd hope that the surgeon would have a DYJS % in the high 90's and would dominate any middle reliever. This suggests the idea of an Employment Adjusted Did Your Job Stat Perentage(EADYJS %), but that is a topic for another day.

1 comment:

mehmattski said...

All right, I've taken some time to think about this post, and here are my thoughts. The idea for DYJS came about while we were playing MVP 2003, and I would pitch and Sam would hit. We would judge our performance in individual games based on whether I limited the opposing team to less than three runs, or whether he scored three or more runs- if so, we "got the job done."

And much like Bacardi and Cola, one thing that the SABRmetric statistics may not capture is consistent ability to get the job done. Yes, RBIs are largely attributed to context (you need people on base in front of you) and slugging percentage (smash! hit ball far!). Digging deeper, Tom Tango (http://www.tangotiger.net) has said that even Win Shares and Runs Created have problems because they do not take into account the dynamic context in which runs are actually created, leading to wins. His Leverage Index attemps to combat this by analyzing all on base/out/inning combinations to determine which are most critical in a baseball game. This contextualizes the baseball game on the level of independent events.

DYJS, meanwhile, looks as though it will contextualize baseball performance on the game-by-game level. That is, out of 162 games, how often did a given player do something that put his team in a position to win.

It will be interesting to see if we can set up a program that charts player's DYJS throughout a season, and whether these numbers correspond to Win Shares or VORP or even to the "clutchitude" parameter on fangraphs.com. If Sam can set up the program, we can even try to run it on the 2006 boxscores to see what we come up with, and maybe tweak the formula a bit. Stay tuned.