Comments on: Pitch Type Linear Weights Explained

By: Ethan

Ethan — Thu, 18 Mar 2010 17:37:59 +0000

Would a pitcher, pitching optimally, have the same linear weights value for each pitch type (because they’d be mixing their pitches to make it so)? In that case, this doesn’t really tell us how good in an objective sense any given pitch was (for that we’d probably use PitchFX data), but rather it tells us how good the pitcher is overall and how well he mixes his pitches.

Or, am I misunderstanding completely?

By: bhinnant

bhinnant — Wed, 17 Mar 2010 21:57:20 +0000

I find this impractical except on a macro theoretical basis. To reach a true linear weighting, you would need to factor in the specifics of a pitcher, the batter being faced, and the defensive ability of the team, plus men on base, plus outs. Otherwise, you equate Rivera in the ninth against Eckstein with no one on and 2 outs as the same as Bruce Chen against Pujols in any inning with bases loaded and no outs. I suspect the real results are higher than the theoretical projections, but you’d need some serious programming to make it work. On the other hand, at one time only wins was a significant stat, so you have to start somewhere.

By: Jay

Jay — Sat, 23 May 2009 15:56:20 +0000

Thanks Dave. That makes sense and just wanted to make sure I was understanding it correctly.

By: David Appelman

David Appelman — Sat, 23 May 2009 13:01:49 +0000

We’re using context neutral linear weights for each event and also a common pitch-count chart for every situation.

The base runners/out situation is never taken into consideration.

I think where the confusion arises is that the weights I’m using are derived by using run expectancy matrix on play-by-play data from 2005-2008 and then taking the average of worth of what a plate appearance through an 0-1 count would be, etc…

By: Sky

Sky — Sat, 23 May 2009 12:28:07 +0000

You’re using run expectancy based base-out state, right? So a strikeout to start an inning has a different pitch value than a strikeout with two runners on and two outs, right? That’s what Dave Allen’s article implies, at least. If not, are you just using typical context-neutral linear weights for all events and a common pitch-count chart for every situation?

By: Dave Allen

Dave Allen — Sat, 23 May 2009 02:24:34 +0000

Jay,

Good point. The value of a single with no outs and no one on is 0.4, but the average value of a single (over all base and out states) is about 0.5.

So the value of the pitch given the out and base state was 0.44, as I showed in the demonstration. But in point of fact, what I do in my articles, and what I think David has done here, is ignore the base and out state and take the average value of the single (or an out, home run, etc). So the value he would attach to the pitch for the Shields’ fastball would be 0.54 as you suggest.

I hope that clears it up.

By: Jay

Jay — Sat, 23 May 2009 00:36:42 +0000

Hey guys i’m understanding you until the single in the at bat.

If i’m correct, you are using this chart: http://baseballanalysts.com/archives/2008/02/writing_about_t.php

Or do you have an updated one you are using?

Because based on the above chart, the run value of a single would be 0.5 and not 0.4.

Also, i’m guessing the numbers are regardless of base state? So a single is worth 0.4 regardless if it’s with the bases loaded or no one on?

Great stuff as always.

By: Gdawg

Gdawg — Fri, 22 May 2009 05:14:58 +0000

This stuff is great, but I have a question about a possible new feature.

With all this information on how a pitcher does for each pitch, are there plans to incorporate this type of data for hitters? This way, you could see who hits fastballs best vs. who the best curveball hitter is or w/e you might be interested in. Or also some specific plate discipline data on specific pitches would be cool too (like swing and miss%, contact%, and all that good stuff).

Anyways, thanks for the explanation and keep up the great work guys.

By: Curtis

Curtis — Thu, 21 May 2009 22:36:36 +0000

You guys continue to surpass even my loftiest of expectations.

Is there a plan to do the same for hitters? I’d love to see the tale of the tape on Albert Pujols vs. fastballs or Ryan Howard vs. sliders.

By: David Appelman

David Appelman — Thu, 21 May 2009 21:34:08 +0000

A fly out and a strikeout in these instances are worth essentially the same amount.

I’m weighting sac flies differently, but over a full season it’s not going to make much of a difference.