Pitcher Evaluations: Post Sticky Stuff Ban Memo

Note: During the All-Star break, at least Paul and I are going to break down pitcher results and they will all be in this article for easy reference. The article will grow throughout the week as more and reports get done. Please submit pitcher recommendations in the comments making sure it’s only actionable pitchers (no Cole’s or Giolito’s).


For those coming back from a two-year submarine tour, here is some background on the current state of the sticky substance ban. Pitchers who use sticky stuff on baseballs create more spin and more spin can lead to more strikeouts for certain pitches. Someone(s) felt it was finally important to start enforcing the rule after decades of turning a blind eye. Here is the time timeline for the crackdown.

  • April 1: Balls were collected that were deemed to have sticky stuff on them.
  • May 15: The spin rate across the league dropped. It almost seemed like teams got a double-secret memo before the official memo.

  • June 15: Official MLB memo came out that stated that umpires were going to start cracking down (leaked on the 14th).
  • June 21: Umpires started checking pitchers.

So there was basically a month and a half when pitchers were applying whatever they wanted. A month when everyone knew a crackdown was coming. And this last month of being checked every inning.

Once the crackdown was going to happen, several people wrote about the potential effects. The Athletic noted the pitches that would see the largest effect from having less spin would be four-seam fastballs and sliders.

Also, we’re focusing only on four-seamers and sliders because, as you can see from this image, the effect of spin on the strikeout rate for at-bats ending with a four-seam and slider are severely affected by how much spin is on the ball.

The relationship isn’t particularly strong in terms of predictiveness — there’s a lot more to the effectiveness of a pitch than just the spin rate — but there is a relationship here that matters.

The same article stated that the average drop in strikeout rate would be 1% point. In a separate Athletic article, Eno Sarris went into a few reasons why pitchers might not be struggling as much as originally predicted.

For one, you see in Codify’s tweet above that velocity has been up a little as spin is down. It could be that pitchers are compensating for the lack of spin by throwing harder, it could be that weather is just leading to faster fastballs, it could be that without some gooey substance pulling back on the ball, more energy is put directly into the fastball, or it could be some combination of some of these factors. Either way, faster fastballs perform better — the slugging percentage this year on a fastball between 92 and 93 is .500, and it drops to .445 on balls thrown between 94 and 95 — so this might be undoing some of the effect of removing spin.

There’s also some evidence that at least some pitchers are going away from the four-seamer and throwing more two-seamers recently, which brings up the specter of in-game type adjustments. Perhaps some pitchers are varying their fastball location more, or their pitch mix, or their velocities — a lot of these things won’t come up in a league-wide assessment, but they could introduce noise to league results.

Simply, MLB has been trying to crack down since the beginning of the season, spin is down, but on an aggregate level, results have not changed.


Dylan Cease

While Cease has not performed the best since the crackdown, the only obvious difference from before and after is his home run rate.

Dylan Cease’s Pre and Post Memo Production
Start Date End Date FF% CH% SL% CU% ERA xFIP K/9 BB/9 HR/9 GB%
4-Apr 12-Jun 48% 10% 30% 13% 3.38 4.07 11.50 3.90 0.80 32%
17-Jun 11-Jul 41% 11% 27% 22% 6.04 3.65 11.40 3.60 1.80 45%

His strikeout and walk are effectively unchanged and his xFIP is down because of more ground balls.

One little small change is the increase in curveball usage. The increased usage has been able to mask that his fastball and slider have performed worse as their spin rates tanked.

Dylan Cease’s Pre and Post Memo Pitch Results
Time Frame Velo Spin SwStr% Velo Spin SwStr% Velo Spin SwStr%
Before Enforcement 95.9 2610 12.2% 85.4 2921 21.6% 79.0 2833 12.8%
After Enforcement 96.9 2369 6.4% 85.3 2748 16.5% 80.7 2663 16.7%
Change 1.0 -241 -5.8% 0.0 -173 -5.1% 1.6 -170 3.9%

It was almost as if the White Sox management and Cease had a pre-enforcement plan to keep his production going. The change might not have been noticeable if he hadn’t had some home run regression. -Jeff

Alex Cobb

Right when the ban seemed inevitable (coincidence?), Cobb went on the IL with a finger blister. Here is his performance divided up by pre-injury, post-injury to the enforcement, and post-enforcement.

Alex Cobb’s 2021 Results
Start End K/9 BB/9 GB% ERA FIP SIv SI FF FS CU
3-Apr 4-May 13.1 4.2 55% 5.48 2.56 92.3 39% 3% 44% 16%
20-May 12-Jun 8.6 1.6 65% 4.50 2.53 92.6 39% 10% 33% 18%
18-Jun 9-Jul 8.7 2.8 50% 2.78 2.72 92.7 43% 10% 33% 15%

He came back post-blister throwing his splitter fewer times, and his strikeout rate is strikeout rate suffered. Since being healthy, he has a 3.63 ERA and it has even matched his sub-3.00 ERA over the last few starts

As stated in the background section, sinkers and splitter results won’t be affected as much by a lack of sticky stuff even though it looks like Cobb was using some by the drop in spin rates.

Alex Cobb’s 2021 Pitch Results
Sinker Splitter
Start End Velo Spin SwStr% Velo Spin SwStr%
3-Apr 4-May 92.3 2174 2.4% 87.4 1721 23.4%
20-May 12-Jun 92.7 2099 6.4% 88.0 1713 16.7%
18-Jun 9-Jul 92.5 1966 5.6% 87.1 1553 21.9%

Simply, it seems like Cobb finally got healthy and the results have improved. -Jeff

Johnny Cueto

Cueto’s spin dropped after the enforcement started thereby leading to a few other adjustments.

Johnny Cueto’s Pre and Post Enforcement Results
Start End FF% SI% CH% SL% FFv K/9 BB/9 ERA xFIP
2-Apr 18-Jun 38% 11% 22% 10% 92.30 7.10 1.70 4.05 4.08
25-Jun 6-Jul 33% 21% 20% 25% 91.10 9.00 2.00 4.50 4.07


Johnny Cueto’s Pre and Post Enforcement Pitch Results
Start End Spin SwStr% Spin SwStr% Spin SwStr%
2-Apr 18-Jun 2296 13.0% 2231 7.6% 2297 5.7%
25-Jun 6-Jul 2159 13.6% 2086 5.1% 2211 3.3%
Difference -137 0.6% -145 -2.5% -86 -2.3%

While he’s lost over 100 rpm off his pitches and over 1 mph off his fastball, his overall results have remained constant (4.08 xFIP vs 4.07 xFIP). I’m not surprised one bit since Cueto has found a way to remain competitive well past his prime. The key stat to keep an eye on is his walk rate. He’s been most productive when it’s been at or below 2.5 BB/9 -Jeff

Max Fried

Fried’s spin rates on all his pitches have remained constant. His struggles are from being lucky last season on balls in play (0.3 HR/9, .268 BABIP) and a little unlucky this year (1.1 HR/9, .327 BABIP). -Jeff

Rich Hill

There is a lot going on here. After being lights out in May (0.78 ERA), he was a replacement-level arm in June (4.56 ERA) and July (4.15).

Several factors have been affecting his talent. First, his velocity has been slowly dropping as the season’s progressed. His average fastball velocity has been as high as 90 mph and down to 87 mph. Second, he toyed around with a cutter for a couple of months and is now doing the same with a changeup. The cutter was ineffective (5% SwStr%) while the change has been decent (13% SwStr%). Finally, the lack of sticky stuff paired with the loss of velocity just destroyed his effectiveness over the last few games.

Rich Hill’s Pre and Post Crackdown Results
Start End FF% CU% FC% CH% ERA xFIP K/9 BB/9 GB%
3-Apr 20-May 42% 47% 7% 0% 3.89 4.32 9.2 3.5 41%
25-May 17-Jun 54% 39% 2% 5% 3.25 3.89 9.1 2.3 49%
23-Jun 5-Jul 46% 40% 3% 4% 4.12 6.52 6.4 4.6 26%
Rich Hill’s Pre and Post Crackdown Pitch Results
Start End Velo Spin SwStr% Velo Spin SwStr%
3-Apr 20-May 89.2 2382 9.2% 73.0 2807 11.7%
25-May 17-Jun 88.5 2332. 11.1% 71.8 2686 10.8%
23-Jun 5-Jul 88.3 2198 6.9% 70.8 2538 8.1%

A 6.52 xFIP? His 4.12 ERA might be a disappointment, but things could get so much worse. Everything is headed in the wrong direction. Strikeouts and ground balls are down. Walks are up. At best, bench him but I could justify cutting him until he returns to form. -Jeff

Kwang Hyun Kim 김광현

Not much has changed between the pre and post-crackdown dates for Kim. He has had very little, if not negligible, change in spin and his velocity remains the same aside from a one tick drop on his slider. Could the drop in fastball spin rate be causing a drop in his swinging strike rate? Maybe. But going from 5% to 2% most likely means that the pitch just isn’t one that misses bats.

Kwang Hyun Kim 김광현 Pre and Post Ban Pitch Performance
FF Slider
Start End Velo Spin SwStr% Velo Spin SwStr%
Apr 17th June 4th 89 2164 5% 84 2138 15%
June 15th July 10th 89 2113 2% 83 2116 15%

Kim’s pitch mix has changed slightly as he used the slider and changeup a little more often in his last few starts. He earned the win in his last three starts. But, looking at both his game logs and some performance metrics, unless I’m missing something, doesn’t show any real indication of big changes.

Kwang Hyun Kim 김광현 Pre and Post Ban Pitch Usage
Start End FA% (pi) SL% (pi) CH% (pi) CU% (pi)
April 17th June 4th 44% 33% 10% 12%
June 15th July 10th 42% 38% 12% 9%

While he walked batters at a higher clip, he forced ground balls and limited home runs. Kim hasn’t allowed a home run in his last four starts and he’s been able to leave runners stranded (LOB%) more often.

Kwang Hyun Kim 김광현 Pre and Post Ban Performance
Start End GS K/9 BB/9 GB% ERA Hard% xFIP LOB%
April 17th June 4th 9 8.1 2.7 44% 4.05 33% 4.23 71%
June 15th July 10th 6 6.4 3.6 52% 1.95 25% 4.74 84%

Kim doesn’t appear to have been affected by the crackdown. He has done well in his last few starts and could continue to be valuable for fantasy teams in the right matchups. He will not boost your strikeout totals, but could help bring down some ratio statistics. In 2021, only five out of his 15 starts ended with more than 1 earned run. That leaves 10 starts where Kim has allowed one earned run or less. -Lucas

Eric Lauer

Lauer is seeing a drop in spin after the enforcement but the decline coincides with a drop in velocity.

Johnny Cueto’s Pre and Post Enforcement Pitch Results
Start End Usage Velo Spin Usage Velo Spin Usage Velo Spin
29-Apr 20-Jun 44.0% 92.5 2253 30.0% 89.9 2361 12.0% 86.1 1498
27-Jun 9-Jul 49.5% 91.9 2209 17.0% 89.8 2244 12.0% 85.8 1509
Change 5.5% -0.6 -44 -13.0% -0.1 -117 0.0% -0.3 12

The biggest loser here is the pitch that turned around his season, his cutter. The pitch’s swinging-strike rate is down from 10.9% before the enforcement to 5.3% after it. Lauer has a decent ERA (0.98) in his last three starts by allowing no homers with just a 28% GB%. During that time, his strikeout dropped from 9.7 K/9 to 6.4 K/9 and his walk rate is up from 3.3 BB/9 to 4.9 BB/9. His value takes a major hit without the cutter’s effectiveness. -Jeff

Shane McClanahan

There is a lot going on with McClanahan so it’s tough to separate any changes from a lack of sticky stuff. He struggled in June with a 5.01 ERA (3.26 xFIP) and that might be from facing a lineup more times. From being called up to his June 9th start, he averaged facing 17.5 batters per game. Since then, it has been 22 batters. He’s definitely been better the first time through the batting order (1st TTO: 3.33 ERA, 2nd: 4.97, 3rd: 3.53)

Also, he’s doubled the usage on his above-average curve (18% SwStr%) from 8% to 16%. Finally, his fastball spin rate is down an average ~60 PM along with his average fastball velocity down 0.6 mph. During the double decline, his swinging-strike rate on the pitch is down from 9.4% to 4.8%. How much is from the velocity and how much from the spin? Or because a hitter is seeing it for a second or third time?

He’s changing but it’s nearly impossible to quantify the exact effects of the enforcement of the rule. -Jeff

Mike Minor

Minor has been able to keep his spin constant and his recent struggles (6.99 ERA since June 1st) are from a declining velocity. His monthly fastball velocity has gone from 91.6 mph to 91.0 to 90.5 to 90.8 and his slider from 86.3 to 85.5 to 85.4 to 84.8. His strikeout rate was 10.2 K/9 for the first two months but just 6.8 K/9 since June 1st. Nearly unrosterable at his current production. – Jeff

Frankie Montas

Montas has had a significant drop in spin (Sarris’ piece marked a one standard deviation drop, or at least 115 RPM, as significant) on both the splitter and fastball. While the velocity has remained stable on both pitches, the fastball has been swung on and missed slightly less often while the splitter has actually increased in swinging strike rate.

Frankie Montas’ 2021 Pitch Results
FF Splitter
Start End Velo Spin SwStr% Velo Spin SwStr%
April 5th June 10th 96 2445 9.81% 87 1846 20%
June 15th July 8th 96 2325 8.83% 87 1596 27%

Perhaps this loss of spin has led to an increased splitter usage, up from 16% before the 15th of June to 25% in his last five starts. This uptick in usage may have contributed to a higher ground ball rate and a lower hard hit rate, which have combined to lower his xFIP, yet his ERA has suffered, likely due to slightly more walks and one bad outing.

Frankie Montas’ 2021 Results
Start End GS K/9 BB/9 GB% ERA Hard% FS% (pi) FA% (pi) xFIP
April 5th June 10th 13 9.4 2.3 38% 4.37 32% 16% 31% 4.10
June 15th July 8th 5 9.6 3.0 50% 4.50 29% 25% 26% 3.75

On June 21st against the Rangers, Montas gave up 8 earned runs and inflated his ERA since June 15th. We’re only looking at a few starts, but his splitter was used more in his last two starts than it has been in any game in his career. The pitch has gone from a pre-crackdown linear pitch weight value of -1.3, up to a post June 15th value of 2.4. See for yourself. It’s possible that Montas has found more confidence in the splitter in his last few starts and we could be seeing a more dominant pitch developing in a post-stick environment. – Lucas

Martín Pérez

In this past week’s waiver wire article, I noticed Perez was struggling so I decided to dive in a little deeper.

It looks like Perez waited until the last minute to quit using the stuff and he’s a completely new pitcher. The weird thing is that all the changes cancel out as seen by his xFIP remaining constant while the rest of his stats jumped around.

Martin Perez’s Pre and Post Crackdown Results
Start End K/9 BB/9 GB% ERA xFIP SI% CH% FC%
6-Apr 13-Jun 7.9 3.2 39% 4.52 4.51 26% 23% 31%
19-Jun 10-Jul 5.9 2.7 51% 2.74 4.47 27% 27% 31%

One interesting note is that his low spin pitches (sinker and change) are missing more bats while his cutter has become ineffective.

Martin Perez’s Pre and Post Crackdown Pitch Results
Start End Velo RPM Str% Velo RPM Str% Velo RPM Str%
6-Apr 13-Jun 84.8 1747 15.0% 89.5 2262 6.5% 92.5 2078 2.3%
19-Jun 10-Jul 84.4 1640 19.4% 89.3 2172 1.7% 92.6 1945 3.8%

His pitch mix has stayed constant (Table 1) but he could definitely try to fine-tune it for peak performance and regain the strikeouts. -Jeff

Patrick Sandoval

No changes to his spin rates. The only recent change is that he’s throwing his sinker (4% SwStr%, 50% GB%) more and four-seamer (7% SwStr%, 45% GB%) less. -Jeff

Brady Singer

As a sinkerballer (50% GB%), none of Singer’s pitches have seen a spin rate drop and all of his June struggles can be linked back to a start when he walked five Yankees. -Jeff

Tarik Skubal

Skubal is having an interesting season and possible changes in sticky stuff have nothing to do with it. The changes revolve around adjustments in his pitch mix. In May he dropped his splitter (10% SwStr%) and went back to his change (17% SwStr%). Then in June, he started throwing a sinker (8% SwStr%, 50% GB%). Here are his pitch usages and results during each period.

Tarik Skubal’s 2021 Season
Start Game End Game FF% SI%, CH% FS% SL% CU% ERA xFIP K/9 BB/9 GB%
4-Apr 30-Apr 54% 0% 0% 13% 27% 6% 6.14 6.86 7.4 5.7 21%
7-May 25-May 54% 0% 17% 0% 21% 8% 4.29 3.24 13.3 2.6 36%
30-May 8-Jul 41% 17% 17% 0% 18% 7% 3.55 3.68 11.0 3.6 42%

With the addition of the sinker, he trading off strikeouts for groundballs.

Looking into his pitches, there are definite breaks when his spin dropped. They were not on the same day which seems to jive with his constant tinkering this season.

Tarik Skubal’s 2021 Slider and
Pitch Start Date End Date Velo Spin SwStr%
Four-Seam 4-Apr 5-Jun 94.2 2246 11.3%
11-Jun 8-Jul 94.2 2127 11.7%
Change 0.0 -119 0.4%
Slider 4-Apr 7-May 85.4 2177 11.5%
14-May 8-Jul 86.4 2072 18.7%
Change 1.1 -105 7.2%

While he’s lost some spin, the two pitches are performing the same or better. While Skubal’s spin has dropped, his pitch mix changes explain his up and down season. -Jeff

Ross Stripling

Stripling has undergone an in-season change, but it wasn’t tied to the sticky stuff ban. After getting trounced for 6 runs in 3.7 innings against Boston on May 19th, Stripling’s season ERA ballooned to 7.20 through six starts. Something had to change.

The advice that Stripling received from pitching coach Pete Walker and bullpen Matt Buschmann was the same: stabilize his glove during the windup. Five days later, he was used as a follower after Trent Thornton opened and he saw quick results: 7 scoreless innings with 7 strikeouts, 2 hits, and 2 walks. He went back to standard starting and has been excellent since the change, posting a 2.90 ERA and 0.97 WHIP in 49.7 innings with a 25% K rate and 8% BB rate.

His last outing before the break is the only true bad one of the bunch (3.7 IP/4 ER at TB). Even with that start included, he has been great since the crackdown with a 3.54 ERA and 1.03 WHIP in 20.3 IP and his spin rates are essentially unchanged. The minor differences fall in line with standard variance suggesting the ban hasn’t hurt him in any real way:

Stripling Spin Rates
Period 4S Spin SL Spin CB Spin CH Spin
Pre-Ban 2181 2356 2546 1675
Post-Ban 2193 2346 2503 1663

As long as he maintained the improved mechanics, Stripling is an all-formats arm who you should start most of the time. If you want to skip an outing, bench him as opposed to using him as a standard streamer and cutting him back into the free agent pool. -Paul

Jeff, one of the authors of the fantasy baseball guide,The Process, writes for RotoGraphs, The Hardball Times, Rotowire, Baseball America, and BaseballHQ. He has been nominated for two SABR Analytics Research Award for Contemporary Analysis and won it in 2013 in tandem with Bill Petti. He has won four FSWA Awards including on for his Mining the News series. He's won Tout Wars three times, LABR twice, and got his first NFBC Main Event win in 2021. Follow him on Twitter @jeffwzimmerman.

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Sandy Kazmir
1 year ago

Mind if I drop a few to get things rolling? I’d love to see Ross Stripling, Dylan Bundy, and/or Brady Singer