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Comment by cratermoon | Hacker News Reader

"The sticky stuff helps increase spin on pitches, which in turn increases their movement"

uh, no. That's not how pitch movement works. How did SI let a writer who knows so little about pitching write this garbage?

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Movement refers to the "horizontal break and vertical drop" of a pitch against the average.[0] If a pitch has more break and more drop then it has more movement. A pitcher can increase these by increasing the spin rate[1]. That's why spin rate is all the rage these days among sabermetric geeks.

[0] https://www.mlb.com/glossary/statcast/pitch-movement

[1] https://www.mlb.com/news/how-spin-rate-affects-curveball-out...

I can’t recall the last time (prior to rules enforcement) I’ve seen a pitcher not grab their hat, glove, or belt before each pitch helped by spin in order to use some form of adhesive. Actual data would be helpful but the impression I get is that literally every team did it and allowed the opponent to do it in exchange.

How do you think pitch movement works? I'm no physicist, but everything I have heard states that spin (or a lack thereof) is the primary driver of pitch movement.

The key is "lack thereof". See for example knuckle ball.

I don't mean to be rude, but I don't think you know what you are talking about here. The benefit a knuckleball gets from its lack of spin is unpredictability in its movement and not movement itself. Outside of the knuckleball, breaking pitches (i.e. pitches with the most movement) generally spin more than non-breaking pitches. For proof you can just take a look at the spin rate leaderboard[1]. Look how far you have to scroll down the list before you start seeing fastballs.

[1] - https://baseballsavant.mlb.com/statcast_search?hfPT=FF%7CFT%...

This accurately describes the magnus effect which powers the majority of the movement that a pitch has.

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