Following up: Reducing spin of spin rates; MLB issues guidelines against substances

Given baseball’s rich history of doctoring its namesake item, I don’t expect Major League Baseball’s new policy on grip-enhancers to end the practice.

However, we can tie up at least one loose end of our discussion on Monday. You may remember that Shane Bieber was the latest high-profile pitcher to suffer a big drop in spin rate during his thoroughly mortal outing against the Mariners on Sunday.

Perhaps the absence of some kind of foreign substance played a part, but another reason for his ineffectiveness emerged when Cleveland placed him on the 10-day injured list with a right shoulder subscapularis muscle strain. He’ll be shut down for at least two weeks, after which he’ll be re-evaluated.

It’s similar to the big drop in spin rate that Lance Lynn experienced around his bout with back tightness in April, so it speaks to at least one factor that hampers that metric independent of the current furor.

Speaking of which, Lynn had to battle through six innings against the Rays, giving up a pair of homers. If you look at the Game Feed on Baseball Savant, you can see that his fastball spin rate also dropped by triple digits.

But when you look at his season-long chart, is it the kind of dip that looks meaningful? Not really, unless there’s more of a slide to follow.

As it stands, his spin rate changes are still around one standard deviation of normal. In a useful article for The Athletic, Eno Sarris and Britt Ghiroli said that pitchers can fluctuate 115 rpm or so over the course of a season, so one might have to double that margin to find a serious offender.

There appears to be a kind of cumulative cooling effect, but it’s going to take more evidence to isolate genuine spin rate issues from other things that muddy up month-over-month comparisons, because offenses usually jump in production around this time of year regardless. For the time being, I just want to understand what I may be seeing when I see a sizable shift in spin rate, most notably what qualifies as “sizable.” So there’s at least a little bit of progress on that front.

* * * * * * * * *

Speaking of MLB’s new midseason policy, the enhanced enforcement will begin on Monday, and as you might expect from any guidelines presented in the middle of a summer without input from the players, it’s a mix of sensible, confusing, and susceptible to loopholes.’s Anthony Castrovince has probably the most straightforward summary of the rules:

Under the new guidelines, any pitcher who possesses or applies foreign substances in violation of the rules will be ejected from the game and automatically suspended in accordance with the rules and past precedent. Suspensions under Rule 3.01 are 10 games. Starting pitchers will have more than one mandatory check per game, and relievers must be checked at the end of the inning when they entered the game or when they are taken out of the game, whichever comes first. Typically, the inspections will take place between innings or during pitching changes to give the umpires ample time to perform a thorough check without delaying the game.

Players will be paid during suspensions for this violation; repeat offenders will be subject to progressive discipline. Clubs and club personnel will also be subject to discipline for failure to ensure compliance with these rules.

This purports to crack down on substances all the way down to the generally accepted combo of sunscreen and rosin, with the league advising pitchers to avoid personal applications in situations it doesn’t apply (games at night or with a closed roof). They also attempt to limit gamesmanship from managers, but it’s inviting Tony La Russa to put his law degree to use:

As always, it’ll come down to consistency of enforcement, and the ability for umpires to actually know what they’re looking at when they assess things like fingertips. It doesn’t seem likely to act as a deterrent if it doesn’t result in at least a couple of notable suspensions. The one part I do like? Any pitcher who is suspended can’t be replaced on the roster, which provides additional incentive for teams to police their own actions. It just can’t rely on peer pressure to see it through, because we’ve seen how little that does.

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There was another loose end from Monday’s White Sox action that didn’t pertain to foreign substances — Tyler Glasnow’s premature exit after four innings. The Rays had to brace for the worst given the way Glasnow was favoring his forearm, and while they’ve avoided the biggest possible blow, the news isn’t good:

The Rays placed Glasnow on the injured list, and called up infielder Mike Brosseau to take his place.

UPDATE: Glasnow says his injury is related to the above topic after all:

(Photo by Erik Drost)

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Jim Margalus
Jim Margalus

Writing about the White Sox for a 16th season, first here, then at South Side Sox, and now here again. Let’s talk curling.

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So a pitcher applies sunscreen to this face during a day game, uses the rosin bag, then wipes sweat off his face. That sounds like its a violation or does that not count as “mixing” them together?


Correct me if I am wrong, but I don’t think that is how players were doing it. It isn’t trace amounts of screen and trace amount of rosin. They were loading up their arm with a ton of both and making a little gummy mixture.


I’m just speaking to the rules MLB is putting in to place. Whether it helps or not, doing that reads like it would be a violation even though everyone knows it wouldn’t do enough to help.


Madrigal out for the year

Last edited 1 year ago by joewho112

Not sure how we should feel about the surgery being done by Dr Nik
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Trooper Galactus

“Whatever happens here today, the law doesn’t have to get involved. One hand washes the other. Oh! That reminds me!”


or the nefarious misdeeds of Dr. Nho
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No Moncada in the lineup today either. Say hello to number 2 hitter: Adam Engel,game_tab=,game=633676


he hits lefties…


It’s going to be interesting if pitchers just learn to become better at hiding it. I was sitting directly behind the Rays bullpen last night, and I got to see each of their routines. It’s fascinating:

Pete Fairbanks – Between every pitch he touches his inner glove with both forefingers, then rubs them on his thumb, then licks the two forefingers and rubs them on his hat, where there appears to be rosin. Seems like maybe he’s making his thumb slick, then getting the substance off his forefingers?

Jeffrey Springs – warmed but didn’t enter the game. This was the guy that was really interesting to me. Between every single pitch, he digs around inside his waist/belt area for just a second. It’s not like his shirt is coming untucked. I started taking some videos to send to a buddy who finds this whole substance thing hilarious. Springs noticed me, then didn’t dig around in there after the next pitch. Once I stopped videotaping one pitch later, he went right back to digging.


That really sucks for Madrigal. Was such a contributor.


Spin rate for stories explaining why certain pitchers do worse come Monday, will go up.


The sox injury luck with star players is starting to permeate around them like a miasma. They’re turning into the Papa Shango of the MLB. So here’s hoping black goo starts bleeding from the head of Correa and Altuve next series!

Just John

The quotes from Glasnow after the injury were interesting when he complained about the ball being “extremely slick”, adding:

“I think whenever I’m trying to hold the ball a lot tighter, it’s probably not going to add to a comfortable elbow feeling. Again, I don’t know. I just think it’d be nice to make it more consistent.”

On one hand, it makes me wonder whether more players cutting the sticky stuff (cold turkey) might visit the IL soon after (e.g., Bieber’s shoulder). Couldn’t a sudden switch to sticky-less pitching alter quite a bit more to general ball throwing than just spin rates?

The first time I read Glasnow’s responses, I wondered if they were sly digs at the new sticky substance policing.


I didn’t think they were sly digs… it was flat out whining. But I’m sure he’s really pissed off from finding out he’s hurt, so I guess stupid stuff will get said. I mean in a nutshell he’s saying, “I can’t cheat like I want so I’m (allegedly) squeezing the ball hard which caused my elbow injury.”


Hold a ball normally. Then squeeze it tight and feel how the muscle in your forearm tense. Those muscles all attach to the elbow on the other end.

Seems entirely plausible that a guy who is throw at the bleeding edge of human capability would increase the risk of injury by being asked to change how they use the muscles in their forearm


I had that happen to my hammy early this year. Since I am old, they did not do surgery. 4 months later, I can run around, carefully at least. I am not a superstitious person , but the Cubs had the curse of the Billy Goat, the W. Sox have the Reinsdorf Curse. Just when they get quality players, the Reinsdorf Curse takes it away.


You’re “not a superstitious person” but you believe in a curse no one has heard of?


Particularly one named after the guy who has owned the team for decades including a stretch where they were know for overall player health


I agree at a high level with Glasnow. Making a sudden and extreme move in the middle of the season is drastic, but it is the right decision based on the decrease in hitting and rampant nature. It’s just madness that MLB would let it get this out of hand (pun not intended).


I am obviously joking about the curse, of which I just made up. But— it would be funny to get back at Jerry’s cheapness and incompetence, and for his making sox fans suffer for many years by associating his name to a curse. Spread it around.