Saturday, June 13, 2020
Root Runs
I posted on Twitter something that is common knowledge among the saber folk, the 10:1 runs:wins relationship.
What is somewhat common knowledge is the relationship of bases and outs to Runs scored. Bill James taught us that with Runs Created, as a function of OBP to SLG.
What might be less common knowledge is how wOBA fits into this. wOBA is scaled to OBP and is proportional to SLG. And therefore, wOBA squared is proportional to runs scored.
However, when we talk about individual players, we really prefer to report in terms of wOBA and not wOBA squared. That’s because, at least for hitters, their impact to a team follows a linear approach, not a squared approach. This is why Linear Weights, not (the basic version of) Runs Created is preferred. And this is why a Runs Created approach that goes through a “theoretical team approach” is preferred. In other words, we can apply the Runs Created concept, but with about 8/9ths of it being linear. I hope that made sense.
So, if we want to know about how talented a team of batters is, we’d average their wOBA, not their wOBA squared (aka Runs). At the individual game level, it gets even worse, because that squared approach will really make larger the impact than it is. In other words, there’s a certain level of “running up the score” because of the way baseball is built.
And so, I thought: why don’t we take the square root of the runs scored and runs allowed? And then take the difference? And wouldn’t you know it: it’s (slightly) better than taking the actual difference in runs scored. I looked at the 660 team-seasons since 1998: 371 teams were closer to their actual W/L record following the Square Root of Runs (Root Runs) approach, while 289 teams were closer using the straight Run Differential approach. That’s 56% to 44%, which is fairly resounding as far as these things go.
The one place I’d be a bit worried, but not too much, is how it relates to pitchers. Pitcher interact with themselves. And so, you DO want a Runs (or wOBA squared) approach. However, adding that up at the game level probably hurts more than it helps. In other words, things get exaggerated at the game level and so, it might still work out going with a wOBA (or Root Runs) approach.
Anything more, and that’s for aspiring saberists to tackle. Actually, the veteran saberists should as well. This is not as obvious as it looks.
Recent comments
Older comments
Page 1 of 150 pages 1 2 3 > Last ›Complete Archive – By Category
Complete Archive – By Date
FORUM TOPICS
Jul 12 15:22 MarcelsApr 16 14:31 Pitch Count Estimators
Mar 12 16:30 Appendix to THE BOOK - THE GORY DETAILS
Jan 29 09:41 NFL Overtime Idea
Jan 22 14:48 Weighting Years for NFL Player Projections
Jan 21 09:18 positional runs in pythagenpat
Oct 20 15:57 DRS: FG vs. BB-Ref
Apr 12 09:43 What if baseball was like survivor? You are eliminated ...
Nov 24 09:57 Win Attribution to offense, pitching, and fielding at the game level (prototype method)
Jul 13 10:20 How to watch great past games without spoilers