@open_command

Open-source command reports! By @tomdoyo (& maybe @lukeblomm)

github.com/tomdoyo/open-command
Joined July 2026
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I'll be using this account to publicly share the results of OpenCommand, a computer-vision based command tracker. Ideas in mind: - MLB command leaderboards - Target maps - Pitcher command trends - Pitcher tactics changes - Reply to this tweet if you have ideas!
Doyoung-Tom Kim
@tomdoyoAug 11
Some news: I decided to open source my command project. It's called OpenCommand. This means anyone can see the code (and even the data)! I hope this gives more people a chance to pursue and share cutting edge baseball research. Anyways, here's how to measure command: 🧵 1/N
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Parker Messick had his 2nd worst command day of the year yesterday. He dropped from 80th to 12th percentile command, walking 4 batters in 2.1 innings.
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3 things are true at the same time: - Command is worth 1/3 Stuff - Command stabilizes almost as fast as Stuff - Adding Command on top of Stuff doesn't dramatically improve ERA prediction Why? 🧵 1/3
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The problem is that command's influence is observable *conditional* on stuff. (Raw command is uncorrelated to ERA) It's a huge survivorship bias (good stuff guys get away with bad command) - there's a negative correlation between stuff and command. 2/3
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So, if command's internal reliability is 0.5 and stuff's is 0.5, we can only observe ~30% of command's effects. Even if command 100% stabilizes at pitch 1, it still needs to wait for stuff to stabilize to be effective. 3/3
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As @pitchprofiler & others mentioned, maybe there's some "minimum command" to be a viable pitcher (throw enough strikes). I managed to find *some* hockey stick going on but it looks like it's driven by K% dropping (not BB% going up disproportionately). It's hard to show in MLB because these pitchers already proved they could throw strikes in the minors!
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For reference, going from worst stuff in the league to best is worth 3 ERA. So, stuff is arguably 3x as important as command (at the MLB level)!
OpenCommand
@open_commandSep 13
Going from worst command in the league to best is worth 1 ERA! There's a strong correlation between xERA (unexplained by Stuff+) and command. And it gets really interesting because some pitch types are way more dependent on command than others (see below)
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Going from worst command in the league to best is worth 1 ERA! There's a strong correlation between xERA (unexplained by Stuff+) and command. And it gets really interesting because some pitch types are way more dependent on command than others (see below)
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Fastballs are almost twice as command dependent as Breaking balls. Anyone have an idea why?
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Note: This wasn't obvious before I managed to remove location leakage from Stuff+ xitter.cf/tomdoyo/status/2097322…
Doyoung-Tom Kim
@tomdoyoSep 8
The biggest remaining flaw with stuff models is that they're secretly location models. Contrary to popular belief, there's a trivial way to adjust for this. 🧵
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Justin Martinez dotted SIX out of 9 pitches during his immaculate inning!
MLB
@MLBSep 12
Justin Martinez pitches an IMMACULATE INNING!
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OpenCommand might actually be the most accurate command tracker in the world. It estimates intended targets with the lowest error! (TL;DR at the end) 🧵
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more replies
TL;DR Measurement errors increase avg estimated miss, so lower avg estimated miss is a good indicator for small measurement error. OpenCommand's target estimation is about 4in (or less) away from true target each pitch. This is among the best in baseball, despite lacking advanced scouting and situational adjustments.
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Thanks for reading. In the future I'll be focusing on analyzing pitcher-batter matchups!
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