Detroit's New Hope
Tarik Skubal dominated in the latter half of 2023. Is he someone to be counted on in the future?
Introduction
One of the most exciting pitchers in baseball is Tarik Skubal, a rising left-handed pitcher for the Detroit Tigers. He was highly touted when he debuted in the majors in 2020, but failed to live up to the hype for his first two seasons, posting a 4.57 ERA in those 36 starts. A great start to his 2022 ended abruptly with a flexor tendon injury, but his return in the 2023 second half built on that success, and blew any realistic expectations out of the water. He posted career bests in virtually every statistic with a refined approach, but some doubts about its sustainability came with it. I hope to look into how much of his improvement arises from concrete changes, and their sustainability for 2024 and beyond.
The Past
To get a better understanding of Skubal today, I think it’s important to look at how he performed in the past. Unlike the pitcher I last analyzed, Blake Snell, Skubal has made a significant amount of changes to his approach and arsenal over his major league career. In addition, he has some important injury history; he had Tommy John in 2016, costing him 1.5 years, and that flexor tendon operation in 2022, which had a year-long recovery.
2020
The 2020 season gives us a brief look at Skubal's repertoire upon his quick promotion to the big leagues (remember, there was no minor league play in 2020). Despite only 9 starts at the Double-A level, and none at the Triple-A level, he was able to hold his own. He posted a 5.63 ERA, mainly from allowing 2.5 HR per 9 innings, but his fastball and changeup were incredibly productive. His main problem was his frequent concession of flyballs, which caused the aforementioned home run problems. Given that these two pitches comprised 77% of his arsenal, he may have been suffering from a shallow arsenal more than anything else; his approach with these pitches is remarkably similar to all of his seasons after that. He also threw his slider and curve at this point, but only occasionally. The slider has stayed remarkably consistent through the years, but his curve debuted with a pitiful 13% zone rate on 8% usage. With a mediocre slider and terrible curve, it's no wonder he turned to his two best pitches so regularly.
2021
Skubal changed things up, adding a sinker to his arsenal to attack all hitters on the armside corner of the plate, to middling results, and cutting his changeup usage in favor of slider usage. His fundamental concern was beating RHB, the group that had given him the most trouble in 2020, so the choice to decrease usage on the pitch best served for beating them, the changeup, is bizarre. He would immediately reverse this decision the following season, but his crucial problem was with the results on his fastball, nonetheless; it had seen virtually no improvement despite a 17% drop in usage. I remember this being a severe point of contention for Skubal at the time, but looking back, a 30.3% HR/FB%, triple the league average, seems excessive for a pitch with a dead average EV on flyballs in a pitcher-friendly ballpark. Skubal's overall metrics tell a much more positive tale here: an above-average 18.5% K-BB% and 3.92 SIERA seem far more representative of his talent than his 4.34 ERA at this point - his issues were in home run luck and pitch mix, rather than the pitches themselves.
2022
Skubal improved dramatically, thanks in large part to a reimagined, even more dominant changeup. He cut the induced vertical break in half, creating a far greater difference in vertical break between it and the fastball. In doing so, it reached the “7/10 rule” threshold with a 7+ mph difference in velocity and 10+ inch difference in induced vertical break. The performance proved the rule, creating whiffs 47.5% of the time and a .193 xWOBA on a criminally low 15% usage.
His most used pitch actually ended up being the slider at 30%, a pitch that remained dependably effective, especially on the inside corner against righties. He dropped his fastball usage dramatically, down to just 24%, but he was much more confident up in the zone with it, certainly in part from that great changeup. His HR/FB rate improved to a more reasonable 15% on the fastball, and his hard contact rate improved across the board. Injury would cut his season short, but it was clear that Skubal was well on the path to dominance with improvements to the changeup and better results from the fastballs.
Skubal Now
The blueprint for Skubal to be successful is clear. He needs to limit home runs on the fastball, turning to the changeup and slider habitually down in the zone, and jamming the occasional sinker inside to RHB, a trend that began in 2022 and was even more present in 2023. Curves are still not much of a factor, but they’re a pleasant surprise to throw in once in a while.
Looking at 2023 in depth, one can see how close he got to that ideal scenario.
Fastball
This is the pitch that saw the most change in 2023. He added 2 mph to the pitch, going from 94 to 95.8 mph, and went with a more height-agnostic approach reminiscent of 2020 and 2021, rather than pounding the offering upstairs as he did in 2022. This change created a 10% increase in zone rate, generating more swings and misses while creating more chases when the pitch landed above the top of the zone and increased its groundball rate by 10%. His 10% drop in home run/flyball rate is unlikely to stick, given that the EV on flyballs is remarkably similar to last year, but he has generated far weaker contact when it does end up on the ground.
The main question here is how much this location adjustment costs his swings and misses. Its whiff rate is identical to a year ago, when the fastball was merely above-average and 2 mph slower, and was chased 10% less. As a result, I'd expect his fastball to get more swinging strikes in 2024, while maintaining an excellent contact quality profile from its relatively low usage (36% overall), velocity, and tunneling with his other pitches.
Skubal’s fastball performance across all four years of his career.
Changeup
The changeup is Skubal's money pitch, and it delivered more than ever in 2023. Thrown nearly a mile per hour harder, he located it low in the zone at a career-high 72%, 12% higher than from 2022 and 24% higher than any year before that. The groundball rate skyrocketed to 62.8%, generating a 27.8% ideal contact rate (ICR), far below the average of 36%, and flyball EV on the pitch was a pitiful 76.7 mph. Most shocking of all is a 28.9% swinging strike rate on a 50.6% whiff rate on a 46% chase rate. Skubal's improved fastball definitely helped, but the elite location on the changeup down in the zone tore right-handed hitters apart. I'm not sure if he can keep the location that elite across a full season, but its performance will likely still outdo 2022, which is a huge compliment given it was still a top-5 changeup in the league then.
Slider
Skubal made the interesting decision to drop the slider’s velocity by 2 mph, inducing 5 more inches of drop than in 2022. He uses it primarily for left-handed hitters to get rollover contact, pounding the zone with it 8% more than league-average, and with an incredible 11% ICR, it still dominates in that regard. It performed worse against RHB in 2023 than in earlier years, but he actually managed to get it down and in against them more often than in years prior. He already decreased its usage by 10% against RHB in 2023, a good choice given the changeup’s dominance and the fastball’s improvement. With so many possible options at Tarik’s disposal to beat them now, I think it might be wise to drop it a little more in 2024. It currently sits at 18% vs. righties, and it may finish as low as 12-15% next season.
Sinker
It is a similar tale to the slider against lefties. It is excellent up and in to induce a 11% ICR, but has much bigger problems than its counterpart against right-handed hitters when they attempt inside part of the plate. He slashed its usage in half against them, from 18% to 9%, and I find it hard to believe it'll go much lower than that, despite its poor performance, due to its tunneling positives. Perhaps it’ll end up at 5%, but it may get retired against RHB altogether.
Curve
It's used exclusively for righties and is clearly his least refined pitch. He uses it to steal called strikes, but the method is predictable. It’s always down and in, and usually so far in it lands for a ball. This pitch has real potential to take some extra usage if he can get more creative with it and find the backdoor (and the zone in general) more with it, but it currently is mediocre at its best.
Adjustment Recommendations
RHB
His fastball and changeup took up 65% of the usage here in 2023, with an assortment of sliders, sinkers, and curveballs afterward. The changeup is so effective that it can take some of the use of the sliders and sinkers, while potentially adding a couple more curves as well. If he went 10% on the curve, slightly up from its current 8% level, with a corresponding 3% increase in changeup usage to a clean 30%, Skubal could go 40% fastballs, 30% changeups, 15% sliders, 10% curves, 5% sinkers. Assuming he maintains excellent command, that will be a tough tiger to tame in the weakside platoon matchup.
LHB
It's almost all sinkers and sliders, with 14% fastballs mixed in, which has worked wonders. It's common amongst online circles to say that same-handed changeups are better than people think (see Logan Webb), and his changeup is so good that it certainly deserves consideration, especially when it sees no usage whatsoever. He sees so few LHBs in the first place (13.5% of all PAs) that what he chooses to throw may not even matter, but he could definitely deepen his mix here with some more changeups and fastballs against them.
Conclusion
Many assume Skubal is doomed for serious regression in 2024, but I've heard that before with mid-season breakout stars. His foundation is excellent - a good fastball with a great changeup, and a solid mix of sinkers and sliders in tow. He also benefits from an improving pitch selection: he has favored the changeup much more than in years past, cut down on sinker usage against RHB, and tuned his approach against LHB to make them virtually unplayable against him. The resulting peripherals in his 80 innings of work are outstanding, albeit mostly against a mix of average to weak AL opponents (min. 80 IP):
2nd in K%-BB% (28.4%, 0.8% behind 1st, Strider)
1st in SIERA (2.77, 0.09 ahead of 2nd, Strider)
1st in xFIP (2.56, 0.19 ahead of 2nd, Glasnow)
1st in dERA (2.10, 0.50 ahead of 2nd, Cole)
2nd in CSW% (33.4%, 0.4% behind 1st, Strider)
1st in DRA (3.32, 0.04 ahead of 2nd, Glasnow)
17th in Pitching+ (107)
It all comes down to whether you believe Skubal could find far better command and velocity at the age of 26 with an arsenal of already good, and improving offerings. He managed to avoid a 2nd Tommy John, but the strength of a brand new flexor tendon from surgery may explain the extra tick of velocity across the board, which has been a clear difference marker. I wouldn’t claim that Skubal is a superstar SP yet, with questions about his ability to find consistent success when his changeup isn’t on point, or against stiffer opposition. Virtually every bad start of his season was on a day where the changeup didn’t dominate! Still, I think you'd have to expect some serious misdirection from his 80 post-surgery innings to believe that he's not in the top 10 at the very least.
Sources:
PitcherList
FanGraphs
BaseballSavant
BaseballProspectus