Where has Tarik Skubal’s spin gone?

The dominant feature of Detroit Tigers left-hander Tarik Skubal is his screaming fourseam fastball. We say “screaming” because throughout his run through the minors and his 2020 debut, the pitch featured superb, high-efficiency backspin that gave it above average vertical and horizontal movement both. Combined with premium velocity for a southpaw, this is the weapon that should carry Skubal to some major league success even as he works to refine his command and his secondary pitches.

Unfortunately, so far in 2020, something is not right with the fastball.

Last season, Skubal’s fourseam fastball averaged 2422 rpms, which is well above the average of 2307 rpms leaguewide. So far in 2021? That mark is down to 2205 rpms through two starts. We also observed the same drop in Skubal’s spring starts where Statcast was available. This is a problem.

The pitch has gained about an inch of drop since last season, and it’s going to make it a little easier for hitters to get the bat on the ball. His whiff rate on the pitch is currently down around six percent, and that has some negative implications for his outlook going forward.

Skubal’s rapid ascent through the minors, and the good outings he managed in 2020, were in part predicated on the ability to throw the fastball right over hitters’ bats with some regularity. His command is still a work in progress, as are his secondary pitches. The ability to throw 60 percent high fastballs and get plenty of whiffs and weak contact was the basis for his approach. Right now, that approach doesn’t look quite as viable.

Of course, Skubal isn’t commanding the fastball so far either. On Saturday night, Cleveland hit two homers off the fastball, and the one mashed by Roberto Perez in particular was right down the middle. His struggles in that outing had a lot more to do with falling behind in counts and missing when he really needed to make a pitch.

Spin can’t do everything for you, and we’re not suggesting that he can’t adjust and be a good starting pitcher anyway. He still has above average horizontal movement on the fastball, and the deception and arm speed are still plenty good enough to call it a plus fastball. He’s just unlikely to get quite the same elite whiff rates he’s previously enjoyed with the fourseamer, and he and pitching coach Chris Fetter will have to make some adjustments to deal with it.

There’s no great explanation for this

Spin rate declines are typically associated with injury or at least marked declines in velocity, and there are no real signs of either with Skubal. His fastball is a tick below last year’s average velocity, but that shouldn’t have near this much effect on the spin rate itself. And since Skubal has posted these rates for over a month now and hasn’t had any apparent injury issue, there isn’t really a viable explanation in that vein.

Right now, the main issue with his fastball command is simply drifting too far toward home plate before his arm is in position to catch up and locate the pitch. Timing, in other words. As a result, he’s leaving a lot of them up and to his armside well out of the zone. Skubal has a rather elaborate delivery, with a high legkick, and a serious crossfire move, so command issues at this point in his career aren’t so surprising. He does ultimately have the athleticism to make it work. But while mechanics could play some role in the loss of vertical movement, it still doesn’t really explain the loss of raw spin rate.

For example, Joe Jiménez has a similar delivery issue. He tends to drive too aggressively with his lower half, leaving himself out of sync with his arm lagging. The result is that Jiménez doesn’t get as much true backspin, and the pitch flattens out. However, he’s has never lost the raw spin to the degree that Skubal has, and what spin Jiménez has lost corresponds more in line with his velocity decline.

The stickier explanation

Perhaps there’s some change in grip that could account for this. Holding the ball with your fore and middle fingers further apart could do it. Gripping the seams differently could perhaps affect spin rate as well. However, Skubal’s slider spin rate is also down this year by about 150 rpms. That’s less a specific concern, because slider effectiveness isn’t tied to spin rate to the same degree as a high-efficiency, Magnus spin fourseamer, but as the drop in spin isn’t isolated to the fastball, it makes it less likely that the cause is anything specifically to do with how he’s throwing the fastball.

There is one other possible explanation. MLB announced over the offseason that they were going to crack down on the use of pine tar or other substances used to get a better grip on the ball. The supposition is that the increased valuation of spin rate by teams had led more pitchers to use something on their fingers to get more spin. Others would say this has always been a very widespread practice, commonly accepted by pitchers and hitters alike, and MLB has another solution in search of a problem here.

On Thursday, it was announced that the league had acquired several baseballs used by Trevor Bauer in his last outing and were testing them for foreign substances. Bauer was the first one to call out fellow pitchers, most notably Houston Astros pitchers like Gerrit Cole, for boosting their spin rates artificially, and later performed an experiment with a substance that, for one game in April 2018, boosted his own fourseam spin rate by about 300 rpms, seemingly to prove his point. Bauer’s spin rate returned to normal in subsequent starts in 2018-2019, but in 2020, he appeared to finally join the crowd full-time. His fourseam spin rate again jumped over 300 rpms on average, and he dominated, going on to win the NL Cy Young Award with the Cincinnati Reds. The league appears to have taken notice.

All this has led to concern about fairness. If the league is going to test balls from guys whose spin rate improves markedly, that means that the many pitchers who’ve been doing this all along are exempt, particularly veterans, because their spin rate readings dating back to 2015 and the advent of Statcast, aren’t going to show a discrepancy. And what happens to the many pitchers who were using something and now have to decide whether to stop, knowing that the change will likely show up in their Statcast data? Seems like most would decide to continue on as they were and hope the zeal for this quickly dies down. Particularly as the possibility of actual punishment remains rather amorphous.

We wrote about this impending crackdown during the offseason, and waited this spring to see if MLB’s long-awaited new baseball with a tackier cover would in fact be ready for its debut. But of course, MLB and Rawlings don’t appear to have cracked the code there, nor have they done the obvious and simply come up with a uniform substance for all pitchers that is better than rosin and approved in the rules. The potential for chaos and self-inflicted scandal seems ripe. Yet, the league has apparently decided they want to crack down on the practice immediately anyway. At least if your name is Trevor Bauer.

So far, the average fourseam fastball across the major leagues is actually registering a slightly higher spin rate than last year—2317 to 2020’s 2307 rpms—so there’s no sign of a widespread change that would indicate that large numbers of pitchers have abandoned using pine tar or some other substance. We looked through the starting pitcher fourseam spin leaders in 2020 compared to 2021, and didn’t find anyone with a decline of over 100 rpms. The one pitcher showing huge spin gains, is Los Angeles Angels starter Dylan Bundy, but his velocity is up 2.4 mph this season, explaining the jump pretty well on its own. Skubal’s velocity is only down nine-tenths of a mile per hour on average, which is pretty typical early in season, and wouldn’t seem to explain quite such a drastic change in spin rate.

So what does this have to do with Tarik Skubal? Well it’s hard not to notice that his spin rates are down to a degree that roughly corresponds with Bauer’s experiments. If Skubal was using a bit of something for grip, and ditched it this year, that might explain the drop in spin rate as well. However, if he did, he seems to be just about the only one, and that doesn’t seem particularly likely either.

Monitor, do not panic

Obviously this is all just conjecture, but there just aren’t many other possibilities. Mechanics, some kind of injury, or something changing in his grip, are the only options. In their postgame comments Saturday night, neither Skubal nor A.J. Hinch wanted to address the specific spin question at all. But until there is a real explanation, or things return to normal, this is going to remain a worrisome development. What isn’t conjecture is the fact that Tarik has lost substantial spin on the heater, isn’t generating his usual high volume of whiffs, and it’s going to require some adjustments to deal with it.

Tarik Skubal still has plenty of weapons. Even with diminished spin, he still carries premium velocity for a lefty and with plenty of deception as well. His slider continues to look better and better, and Skubal is using his huge 12-6 curveball more this season. While his new splitter is still coming along, that too could be a fine weapon for him with more work. He’s a big, athletic power pitcher with plenty of weapons on the mound.

So none of this is to suggest that Skubal can’t develop into an excellent major league starter anyway. The margins, however, may be a little tighter than they were for him previously, and this will be worth tracking as the season progresses.