Foreign substance enforcement didn’t bother the Tigers much in 2021

As the Arizona Fall League enters the final two weeks of the 2021 season, an experiment is taking place that could be a game-changer for pitchers. As Baseball America reported on Saturday, the second half of the AFL schedule will be conducted using balls constructed with a naturally tackier cover that the typical MLB ball rubbed up in mud. Assuming things go well, we may finally have a reasonable solution that provides all pitchers quality, uniform grip on the ball without the need for any foreign substances.

Prior to the AFL season, teams and players were informed that the league would use one set of balls—the usual MLB ball rubbed up with mud prior to use—during the first half of the season, before switching to the new tacky covered balls for the final three weeks of play. As a result, MLB should get stable before-and-after data from the season, with the same pitchers using both sets of balls over a roughly similar sample size of game play.

Anecdotally, things are still up in the air. Some pitchers have found the tacked up balls to be a very effective compromise. Others have complained of substantial inconsistency in the application of the spray-on substance, and voiced concerns as to how they’ll perform in variable weather conditions. Still, this seems like a step in the right direction. More fine-tuning will be required apparently, but we do appear closer to having a solution to make the balls grippy enough to command and spin, without the application of Spider Tack, Firm Grip, or anything else that can provide outrageously high spin rates.

Last January, we anticipated that a leaguewide crackdown on sticky substances was coming. We also anticipated that the move would prove a self-inflicted public relations debacle if not well handled, and as expected, the league didn’t handle it particularly well. Waiting until well into the season was a terrible decision, as the news of MLB’s intention to search pitchers regularly immediately sent fans off, likening a common practice to a cheating scandal on the order of the Houston Astros. It also lead to pitchers freaking out about potential injury and ineffectiveness without time to adapt, and quite a bit of confusion in general.

However, because there was at least ample warning before strict enforcement began, some of the effects of making the decision mid-season were presumably mitigated, as there were very few actual punishments laid down on pitchers during the course of the season. Perhaps the umpires were just wisely judicious in enforcement, looking for egregious rule breaking rather than holding strictly to the letter of the rules. Or perhaps most pitchers did simply choose to comply to avoid punishment.

Interestingly, and probably to the league’s dismay, there was also little sign of this helping to produce more offense, as pitchers continued to dominate anyway, despite the lack of innings thrown in 2020 and a lot of additional injury concerns. League wide strikeout percentage was actually up two-tenths of a percent from 2019’s averages, and league ERA went from 4.51 to 4.27.

So, all in all this proved to be somewhat overblown, by me included. The league didn’t handle it well, but performance wasn’t affected enough to wreak the level of havoc expected, and other than Tampa Bay Rays’ starter Tyler Glasnow, whose UCL tear coincided with the crackdown, pitchers reported only some minor discomfort as they abandoned the advanced sticky polymers for the rosin bag.

Tigers spin rates

Of course, this doesn’t mean individual pitchers weren’t affected. And it’s interesting to note that some of the Tigers’ higher spin pitchers weren’t affected at all, perhaps making their stuff stand out just a bit more against a backdrop of other pitchers losing some spin. Just to satisfy our curiosity, let’s take a look at the average fastball and breaking ball spin rates from a selection of Tigers’ pitchers in both 2020 and 2021. We’ll use (BB) as a catchall for each pitcher’s primary breaking ball, and either fourseamer or sinker depending on which each pitcher uses as their primary fastball.

Generally speaking, a change of 100 rpms or less isn’t meaningful. Slight adjustments in grip or release, or an increase or decrease in average velocity can have an effect, but usually you don’t see much variation beyond 100 rpms. And of course, we have to keep in mind that raw spin rate is more of a descriptive metric than a qualitative one. All things equal, more spin is generally better than less, but at best that rpm number only indicates likely stylistic traits. It doesn’t predict success or failure for a pitcher overall. There are many more important factors at play.

Clearly, Tarik Skubal was the one Tigers’ pitcher who saw a marked change in fastball spin rate, as noted early in the 2021 season. Skubal’s fastball dropped 231 rpms on average between 2020 and 2021, and so one might conclude that Skubal was using something for grip that became a liability. Interestingly, the Tigers do seem to have anticipated the rule enforcement, as Skubal’s spin rate loss was noted early on in spring training.

The effect on Skubal’s fastball was pretty clear as well. The guy who whipped fastballs right over the bats of every hitter he saw on his rapid march through the minor leagues was not in evidence this season. Per Statcast, he lost an inch of vertical movement, and over four full inches of horizontal movement. Skubal’s velocity, angle, deception, and extension all still allow him to rack up a fair amount of whiffs on the fastball, but overall he got crushed as hitters posted a whopping .611 slugging percentage against the fourseamer.

We’ll break down Skubal’s full season shortly, but suffice it to say he showed good signs of adapting via improvements in his slider and changeup, and was more effective when he threw less fastballs overall and mixed in the sinker to keep hitters off-balance. That ability to evolve speaks well for future improvement, but that profile is pretty different than you would’ve read in a 2019 scouting report on him.

Otherwise, the Tigers returning pitchers seemed little affected. The higher spin guys like Jose Cisnero and Joe Jiménez still posted very high spin rate marks. The low spin guys, as you’d expect, stayed basically the same, and even guys like Casey Mize and Matthew Boyd, who are kind of in the middle, didn’t see a major impact on their spin rates.

It will be interesting to see how the league approaches the issue in 2022. Perhaps they’ll feel they made their point and relax enforcement, focusing mainly on players with marked jumps in spin rate. Maybe umpires will tire of the hassle of checking pitchers, become predictable, and pitchers will find it easy to get a little spin back without getting into trouble. Or perhaps, they’ll dial in the pre-tacked baseballs and be ready to give them a go as early as the 2022 season.

A uniform tackier cover, or an agent that can be uniformly applied for the same effect, has long seemed the best solution and has already been put in place in Japan and Korea. MLB has been talking about doing something similar since at least 2015, and simply never put anything into practice. As is so often the case, the league let a problem get out of hand when there was ample evidence of an issue, and viable solutions available. However, they do appear to finally be closing in on an answer that should create a level playing field. Once they have that in place, enforcement should be pretty easy and less intrusive, and the league can simply look for huge pops in spin rate and investigate those pitchers specifically.