Why Spencer Turnbull Can Still Break Out

Sometimes the next hidden star is right in front of you.

Spencer Turnbull is one of the players I’m most excited to watch this season as he hasn’t seen MLB action since June 2021. He started the 2021 season a month late with, what the team described as, “Covid-19 related reasons.” Upon his return, he laid waste to hitters for a month and a half including a no-hitter against the Mariners. Just nine starts into what should have been his breakout season, he went down with a forearm strain. Six weeks later he had Tommy John surgery. Just like that, he was gone for a year and a half. He returned to live competition during this year’s Spring Training and, very importantly, his velocity was exactly where he had left off.

Turnbull is unique in that he has 4 pitches that could reasonably be categorized as plus pitches, at least by stuff measures. This alone is a great base for success but what could potentially put him over the top is that each pitch has a unique movement type without any extremes that make them identifiable out of his hand. I’m going to go through them pitch by pitch to explain why they work. (This report is based on what he was doing in 2021)



The 4-Seam


Turnbull’s 4-seam is an oddball of a pitch featuring a lot of gyro spin with inferred movement direction at 12:26. This leads to very little arm side movement in addition to well below average rise as it makes use of just ~60% of its ~2500 RPM spin rate. As you might imagine, this is a low percentage, especially for a 4-seam. He doesn’t create a particularly unique angle with his release point either. Considering what 4-seam fastballs typically aim to accomplish, this pitch couldn’t miss the mark much harder if it tried. And yet… it works. It’s always garnered more whiffs than the league average while also inducing poor contact. Does it make sense? Perhaps in that if a pitch is unique it stands a good chance of performing well based on being different from everyone else. The more important question: Does it have to make sense as long as it keeps performing the way it has?


Spencer Turnbull’s 4-seam (2020-2021) League Average 4-seam (2020-2021)
Spin/Active% 2499 RPM, 60.2% 2282 RPM, 89.9%
IVB 11.7” 16.0”
HB -2.4” -7.2”
CSW% 32.1% 28.3%
xwOBA 0.328 0.353


The Sinker


Coming in at 94.9 mph with -17.1” HB, just 7” IVB, and a release point 5.7 feet off the ground, his sinker establishes itself with a solid shape thus giving him 2 very good fastballs that play off of each other reasonably well. He has no tells in his delivery or release point that give away which fastball is coming. Like his other fastball, he locates it well and can do so in multiple locations. Being able to land a sinker with as much run as his isn’t easy yet he finds ways to use it to complement his other pitches. Such as running in on the hands of a right-handed hitter, where it looks like a 4-seam down broadway at first, or landing it on the low glove side corner to steal a strike.




The Slider


His slider is more of what I would call a “traditional” breaking ball. It’s not one of the trending archetypes of sliders as it falls in between what would be classified as a gyro slider or sweeper. His slider leaves his hand at 85 mph, breaking 7” horizontally with minimal vertical movement as it goes to the plate. It tunnels nicely with his 4-seam while also being a good pitch in a vacuum. He locates it exceptionally well, being able to zone it on command or place it just out of reach of a hitter while keeping it close enough to be enticing. If he had more confidence in his curveball it would also serve to set that pitch up as the slider lies almost squarely in between his fastball and curveball in terms of its movement but we’ll touch more on that shortly.



The Changeup


The changeup is… confusing. Stuff+ metrics have a difficult time quantifying changeups in general. Sometimes they’ll have what seems like mediocre shape but be effective due to a pitcher’s deceptiveness with the pitch. Other times they’ll look great on paper and pretty to watch but they don’t perform well. The sample of changeups Turnbull has thrown in the majors isn’t particularly large but it is enough to show that his changeup leans toward the latter description. It has what on paper looks like an excellent movement profile. Its induced movement is almost purely horizontal which gives the pitch impressive depth to go along with its excellent fade. It comes in at 87 mph putting it in the sweet spot for having enough velocity separation from his fastballs without becoming identifiable to a hitter by its velocity alone. Despite ticking all the boxes, it’s never really performed well at the major league level. It doesn’t miss bats anywhere close to the rate you may expect. It hasn’t drawn swings out of the zone. Like most changeups, when contact is made the results aren’t exactly pitcher-friendly. Frankly speaking, I’m not sure what to make of this. He may have a tell in his delivery when it’s coming or perhaps his command of the pitch is poorer than it seems to be. Regardless, while it shows potential, the pitch has yet to give Turnbull a good enough reason to throw it more often than he does currently.




The Curveball


Lastly, Turnbull has a curveball that he throws about as often as the changeup– just 7% of the time. This time the reason for the low usage is more clear. While it has a ton of movement (-11.5 IVB, 10.5 HB) with velocity in the high 70s to low 80s, he just doesn’t have a great handle on it. With improved command, it could be useful as a strike stealer or potentially even as a two-strike pitch but it’s just not there at the moment. It should also be capable of garnering chases below the zone especially if set up with his slider and 4-seam fastball.




Keys To Success


The key to his success primarily lies in not defaulting to his fastball in pressure counts and trusting the rest of his arsenal. He’s had a habit in his career of being predictable in high-leverage situations and leaning on the 4-seam to get him out of danger. While it’s a great pitch, he has too much else to offer to allow hitters to sit on one specific pitch out there. I want to see him work to expand his usage beyond the two fastballs and the slider. This is more of a case where he’s already a decent pitcher but there’s enough potential there for him to be the SP2 on a really good team. Or, for now, the ace of his Detroit Tigers.


Stumbling Out of the Blocks


So… let’s talk about those first two starts of the season because they didn’t go according to plan. Let’s focus on the good first, what little of it there was. He’s still working 92-95 mph with the fastballs. The changeup and slider still have their bite. The curve is still at a respectable velocity and, actually, swept a little more than normal. He even did what I was hoping he would do by leaning on his entire arsenal.

Now for the not-so-good. 

In the first start, he was missing with his 4-seam on the glove-side pretty consistently and wasn’t setting up his pitches well. There was very little cohesion in the way he was executing his pitches. He couldn’t seem to get the slider to go where he wanted and the changeup was missing by too much to get any chases. It was a mess.

In the second start, he tried a different approach. After abandoning his sinker during the first start, its usage was more in line with the rest of his career. His locations for it were a bit odd but they got him some called strikes at least. However, way too many of his fastballs were finding the middle of the zone and he didn’t get a single whiff with either of them despite 23 swings combined. He only got one whiff all game with a changeup in the dirt which I’m surprised Devers even offered at in a 1-0 count.

I have two major concerns with Turnbull right now and they stem from the same core issue. Firstly, his 4-seam isn’t fooling anyone so far. It’s not missing bats and it’s getting clobbered. It is moving less than it used to due to lower spin activity and I believe that difference is what’s caused this crater in its performance. It’s gone from a unique gyro fastball to what is, essentially, a bad cutter similar to Garrett Richards’ fastball. Similarly, his sinker is also at a much lower spin efficiency and is missing 4.3″ of arm-side run from its previous shape. This new lack of run makes it much more generic and hittable. He NEEDS to get this spin efficiency drop sorted out soon. I believe his command will return as he gets back into the flow of starting again and is more pitches removed from his long absence. The rust doesn’t always come off right away but I think he’ll shake that eventually. Hopefully, his fastballs will be figured out by then too. The first two starts were terrible but I still have hope he can put it all back together again and recapture what he had in 2021.

Jack Foley

Jack is a contributor at Pitcher List who enjoys newfangled baseball numbers, coffee, and watching dogs walk by from the window where he works. He has spent far too much time on the nickname page of Baseball-Reference.

2 responses to “Why Spencer Turnbull Can Still Break Out”

  1. Noah Dengler says:

    Great write-up, very sound analysis of a potential long-term turn around that could be a difference maker!

  2. Scott Chu says:

    I hope this is true because these Tigers are dreadful to watch right now.

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