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.

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

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

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

Doesn't explain the K% hockey stick though

Yeah idk what's going on

Oh yeah there is, worse command pitchers have better stuff, but the hockey stick with K% (might) mean worst command pitchers have worse stuff which is weird

On the surface it means the opposite: the worst command pitchers also have worst stuff. This is despite removing position players. But maybe there's something in what you said, maybe there's only so much a good stuff helps you with chase

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!

👇

There should be but I'm not sure what the y axis should be in that case

Good point but it's stuff-residualized so the only survival bias we have are pitching iq, arsenal effects etc

That's actually a good take. I should look into whether there's some sort of a command threshold to be part of the MLB

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)!

Yeah maybe because their chase rates are way lower

Note: This wasn't obvious before I managed to remove location leakage from Stuff+ xitter.cf/tomdoyo/status/2097322…

Fastballs are almost twice as command dependent as Breaking balls. Anyone have an idea why?

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)

Justin Martinez dotted SIX out of 9 pitches during his immaculate inning!

Thanks for reading. In the future I'll be focusing on analyzing pitcher-batter matchups!