Randy Dobnak the unlikely... ace?

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By now, readers of this site are quite familiar with the story of Randy Dobnak, unlikely major league pitcher and so far in 2020, unlikely Twins’ ace. I won’t rehash his origin story in this piece, but if you aren’t familiar, I highly encourage you to read about him in these excellent pieces at other sites:

What I want to do today is offer a breakdown of Dobnak by putting his results thus far in context, assessing how he’s achieved those results through his arsenal and approach, and looking at what it all might mean going forward.

I think we’d all be forgiven for being cautious and holding our breath a bit when it comes to Dobnak. For as great as the story is and as much as we enjoy the success he’s had, in the back of our minds I think a lot of us wonder things like is this real? And, when will the bubble burst? That’s human nature. This kind of success doesn’t come from players with such low-profile pedigrees very often. But let’s try to be objective and see what the data tells us.

Career to date:

An undrafted minor league free agent signing, Dobnak found almost immediate and sustained success in his minor league career. In just shy of 300 innings, across five minor league levels 2017-2019, Dobnak posted a combined 2.57 ERA, 1.82 BB/9, and 6.54 K/9. His highest ERA at any stop was 3.14 over a full 2018 season at Cedar Rapids. The ERA and BB/9 are great marks but the K/9 is pretty pedestrian. But Dobnak is able to counter his relative lack of strikeouts with an ability to get groundballs – doing so at a rate above 45% at every stop. This rate increased in 2019 as he progressed through the high minors – 59.1% at Ft. Myers (High-A), 58.8% at Pensacola (AA), and 61.1% in Rochester (AAA).

Still, despite the minor league success, Dobnak debuted with the Twins with little fanfare. And all he’s done since coming to the big leagues at the end of 2019 is pitch better than he did in the minors. In 48.1 career MLB innings Dobnak has a 1.30 ERA, 1.86 BB/9, and 6.33 K/9. His MLB groundball rate is 58.5%. Incredibly and improbably, Dobnak’s MLB numbers are essentially the same or better than as his minor league numbers across the board.

Comparing to the rest of MLB

While Dobnak has performed consistently with his past performance we need to understand that performance in the context of other pitchers. In a vacuum, he’s been excellent – but how does he stack up with his peers?

In the last two seasons there are 220 pitchers that have thrown at least 30 innings as a starting pitcher. Dobnak ranks first in ERA at 1.37, a figure that is 72 points better than the pitcher in the 2nd slot. Of those 220 pitchers Dobnak is the only one not to have allowed a home run. Considering the lowest career ERA in history for qualified starters is 1.82, an ERA that low likely isn’t sustainable. But still it’s impressive stuff!

But these are outcome stats based on a small sample size – only 39.1 IP across 9 starts. How do we know if it’s real or a fluke?

As many others have said before, including Gleeman in his piece linked above, for pitchers to have sustained success they need to be able to do some combination of the following:

If a major league pitcher can do two of these things consistently they will have regular success. These are the main ideas behind defense independent pitching stats, most popularly summarized with Fielding Independent Pitching (FIP).

The most effective way for a pitcher to prevent runs is to prevent batters from putting the ball in play. It’s very hard for a pitcher to be hurt by swings and misses and called strikes. As noted above, Dobnak isn’t a standout in this area. His 6.18 K/9 as a big-league starter ranks just 198th out of the 220. However, that’s not to say he doesn’t get swings and misses. A more granular data point is swinging strike rate, which casts Dobnak in a more positive light. Dobnak gets a miss on an above average 10.8% (89th of 220) of the swings batters take against him.

The next best alternative to strikeouts and swings and misses is generating contact on the ground. Fly balls create extra bases (especially homeruns) and lead to quick runs allowed. Ground balls often create only singles; and it usually takes multiple singles strung together to create a run. Generating contact on the ground is our man’s calling card. His extreme groundball rate (59.3%) is third best overall, behind only Dallas Keuchel and Astros’ lefty Framber Valdez.

On the control front, free bases do nothing but hurt pitchers. Base runners are opportunities to give up runs. In this area, Dobnak has posted a 2.29 BB/9 as a starter. While this is higher than he showed in the minors, it’s still very solid and ranks 41st.

Altogether, that combination of outcomes works out to a FIP of 2.77. Certainly, the FIP number indicates his ERA results have over-performed, but 2.77 is outstanding. In fact, that figure ranks fifth best in all of baseball, trailing only Max Scherzer, Tyler Glasnow, Jacob deGrom, and Gerrit Cole. That’s some impressive company. Even if Dobnak “regresses” as this underlying predictor suggests he should, he’d still be keeping company with arguably the games’ best pitchers.

Fantasy baseball writer Alex Chamberlain pointed out in a post last week on Fangraphs’ Rotographs blog that Dobnak’s combination of skills are rare. Chamberlain found there has been 39 qualified pitcher seasons in the last five years with a better than 50% groundball rate and better than 10% swinging strike rate. If we also account for Dobnak’s good control and add a third criteria of a walk rate less than 5.5% that list shrinks to just three seasons:

I expanded the time horizon to the past ten seasons and found only 8 seasons meeting those criteria. The table below details those, and... it’s quite the list of names:

From this list, only Jeff Samardzija in 2014 did not receive Cy Young votes. It’s worth pointing out here that each of the seasons listed above covered more than 180 innings. So Dobnak, with only 48.1 career innings, has a long way to go before we can be sure he belongs in this company. But it’s illustrative of how unique and elite his success has been and an indicator that he has the combination of skills to sustain some of it.

How well equipped is he to continue on this path?

Dobnak’s Arsenal

Something interesting happened with Dobnak in the low minors. In his first three minor league stops in 2017 and 2018 his ground ball rate was in the mid-40s (save for a 7 inning sample at Cedar Rapids at the end of 2017). Since then his groundball rates have been well above 50% and usually around 60%.

Dobnak operates with four pitches from a low three-quarters arm slot: the sinker (46.4%, 91 mph), a slider (31.5%, 83 mph), a changeup (16.4%, 85 mph) and a four-seam fastball (5.7%, 93 mph). Against right-handed batters he’s relied more heavily on his slider (31.5% RHB / 25.4% LHB) and against lefties he’s brought in the changeup more (21.9% LHB / 10.1% RHB).

There’s nothing overly complicated about that approach and the velocity figures are OK but not outstanding (36th percentile per Statcast). Thanks to Statcast, we also have detailed data on how Dobnak’s pitches move relative to his peers. From it we can discern where Dobnak excels is in pitch movement, especially vertical movement on the sinker. As he pointed out to Gleeman, he learned a new sinker grip with the help of the Twins development staff in Cedar Rapids in 2018. And that new sinker is something special.

Of 2020 pitchers that have thrown 100 or more sinkers, Dobnak has the second most downward vertical movement, averaging 33.4 inches. The only sinker with more absolute downward movement belongs to Boston’s Ryan Weber at 33.9 inches, but his averages only 88.1 mph. That downward break is what generates the groundballs – yielding an average launch angle of -7 degrees and a ground ball rate of 78.1%. Batters can’t help but to hit the top half of the baseball and beat it into the ground.

The sinker alone is impressive and it also pairs well with his slider and changeup. On the right side of the chart above you can see the movement profiles of Dobnak’s four pitches in relation to each other. The slider is shown in yellow with 39.5 inches of vertical and 1.6 inches of horizontal break on average. Naturally, the sinker and the slider break opposite from each other. When you consider the sinker’s 15.3 inches of horizontal break to his arm side and the slider’s 1.6-inch break to his glove side, Dobnak can essentially move the baseball the full width of home plate (17 inches) from pitch to pitch.

You might also have noticed above that his sinker and changeup (orange and green dots on top of one another) are extremely similar in movement. This is an interesting point of deception for a pitcher. The two pitches will look the same in terms of shape and break, but the changeup comes in 6 to 7 mph slower in velocity, adding another challenge for the hitter to deal with.

Dobnak can maximize the effectiveness of these pitches’ characteristics and deception by throwing the changeup and sinker in similar locations (arm side, down) around the strike zone and splitting the sinker and slider (glove side, down) opposite of each other. That’s exactly what he has been doing so far in 2020:

The net result of these combinations is that Dobnak gets swings and misses with the off-speed pitches. While the sinker has only a 6.3% whiff rate, his slider generates whiffs 31.6% and the changeup 25%.

Dobnak has another peculiarity that helps make him successful and it’s one that you wouldn’t expect for a sinkerballer. Andrew Bryzgornia first pointed this out over at TwinsDaily last week. In addition to all the grounders, Dobnak also generates a weirdly high number of infield pop flies. According to data at Fangraphs, Dobnak’s career infield fly ball percentage is 13.3%. It doesn’t appear to be a statistical anomaly either – at every stop of his minor league career his infield fly percentage was greater than 13%. The major league average for infield fly balls is generally just below 10%. It’s worth pointing this out, even though it’s counterintuitive and small numbers, because it’s yet another way that Dobnak compensates for his relative lack of strikeouts. When more than 70% of the batted balls against you are on the ground or harmless pop-ups, you can have a lot of success with just a modest number of strikeouts.

2020 Adjustments

As he adjusts to the major leagues and continues to develop he’s continued to tinker with his approach. In his appearances at the end of 2019, his combined sinker and four seam fastball usage was approaching 60%, with about three out of every five heaters being sinkers. This year he’s mixed in his breaking ball and changeup more, reducing his combined usage of fastball varieties to 52%. He’s also modified that mix to rely more heavily on the sinker – nearly 9 out of every 10 fastballs he’s thrown have been sinkers.

That additional reliance on the sinker may be due in part to the fact that he’s found some additional movement on the pitch. The 33.4 inches of vertical break I mentioned above is almost 2 inches more than his 2019 average. The 15.3 inches of horizontal break is an inch more. In investigating that, I found that a likely cause of this additional movement is that he has also lowered his release point slightly:

Per BrooksBaseball.net, Dobnak’s sinker release point ranged from 5.4 to 5.6 vertical feet in 2019. So far in 2020, its been 5.2 and below. His other offerings have had a similar drop in release point. The change isn’t huge and it’s hard to know for sure if it was intentional. Pitchers experience slight variation in their releases all the time. But this may help explain the subtle addition of movement to his sinker and will be worth monitoring as the 2020 season continues.

Looking Forward

Of course, it seems silly to think Dobnak will maintain an ERA of 1.30 for the rest of his career. As the 2.77 FIP and other ERA estimators point out, Dobnak’s ERA will almost certainly increase over time. Those analytic tools all peg him somewhere between 2.77 and 4.09. Fangraphs’ hosted future projections by Dan Szymborski’s ZiPS tool forecasts 4.33, 4.20, and 4.18 ERAs for Dobnak for 2020, 2021, and 2022. Before you come away disappointed by those figures, consider that the Major League average ERA for starting pitchers in 2019 was 4.54. In the American League it was 4.76.

The point is, by almost any measure you can find, Randy Dobnak looks like a legitimate above average major league starting pitcher. That’s an incredibly valuable thing for the club, especially when you consider that Dobnak essentially came out of nowhere and remains under team control until 2026.

And who knows, Dobnak might very well continue to exceed expectations. After all, he wasn’t supposed to be here, or this good, anyways. He’s already demonstrated an ability to make adjustments that maximize his skills and chances for success. His arsenal and approach seem to suggest there is staying power here.

If he continues to coax obscene rates of ground balls, keeps the ball in the park, and avoids giving away free passes, chances are pretty good that he’s going to be good for a while. The track record of the data and the profiles of his pitches make it seem likely he’ll continue to get grounders. If he can continue to throw strikes, perhaps this is a mid-rotation major league starting pitcher. If he continues to develop and finds a few more strikeouts, maybe the ceiling is higher still.

It’s no longer a question if Dobnak belongs in a big-league rotation, it’s now a question of how good he can be.

John is a contributor to Twinkie Town with an emphasis on analytics. He is a lifelong Twins fan and former college pitcher.


A lot of incredible and deep insight!

Thanks so much for all these unknown details and the insight that I’d never have dreamed possible for Dobnak. It’s truly amazing what he has done so far, not just this year but going back to last year, minus the post-season start of course. And as you showed, his minor league numbers were impressive as well. Some might say this would be obvious, but there are a ton of MLB’ers which includes HOF’ers that struggled in the minors at one time or other.

It never even occurred to me that Dobnak rarely gives up the long-ball til you mentioned it. Only one so far in his career in the big leagues. And what you said about his ground ball rate increasing speaks volumes to why the homeruns aren’t happening against him. I’d be curious to know if starters that throw from the low three-quarters arm slot with most of their pitches have more success (in general) than over-the-top pitchers. And the fact that he has somehow managed to get additional movement on his sinker this year is impressive as well. Again, I’d be curious to know if he got this from Wes Johnson, or another pitcher’s advice, or something he did on his own.

Thanks again for this excellent breakdown of Dobnak. It’s exciting to see him pitch, and am really hoping this can continue for a long time to come.

Why minus the postseason?

I personally still think he was doing fine and with his extreme ground ball rate could very well have worked out of it. This is only suspicion though as Rocco really doesn’t seem to trust him or give him and rope to work with, despite the stats this article provides. He always seems on a short leash, just a threat away from getting the hook even if he hasn’t actually allowed anything.

Maybe I’m just channeling all our ex-pitching broadcasters, but how can we find out how good & real the guy can be if he never gets a chance to deal with adversity or working out of a jam? Sometimes you just have to let a guy face pressure situations to get better in those spots.

Even his start (1 or 2 ago) where he was doing well and only at like 60 pitches, but it was 3rd trip through the lineup so he got pulled. I like the story, I like the guy, I like the results, i strongly dislike how he has been handled unless there is some info we don’t have like that his arm unhinges and falls off on his 83rd pitch.

Good point. If we didn't have such a strong bullpen, I'm sure he'd get a chance to pitch a bit deeper sometimes. But you're right, the leash does seem short at times.

Even with this bullpen

I think more chances are given to Jose & Odo then will ever be to Dob. I’m not sure if it’s so early into his career that Rocco thinks his confidence would be shaken by a bad inning/start or what. His outlook about it when it was talked about around playoff time last year makes me think he has a good enough perspective on it not to worry. I’d be more cautious that it sours/shakes him that the staff apparently has no trust/faith in him once a guy or 2 get on base.

Atta Dobby.

I’m becoming a believer.

How cool would it be

For Dobber to get another Yankee Stadium postseason start—and shut them out this time. What a story that would be!

That would be the ultimate.... especially if it's a series-winning-game that eliminates NYY from the playoffs.

another good start

Well he finally gave up two home runs yesterday, on a couple of sinkers he left up — but he still only gave up a total of three hits and two runs in 5 1/3 innings! That’s not a bad line, for an off day!

It’s possible he will eventually settle in with an over 4 ERA, and as the writer suggests that would still make him a great find. But if he keeps pitching like he is now, he could very realistically outperform that. And hell, he could keep getting better! If he can add new pitches and new movement and improve that much while still a rookie, who is to say this is even his ceiling? His combination of movement and command makes it seem like his results right now are anything but luck. As of now, he’s a serious candidate for rookie of the year and a start in the playoffs.

Remember all the back and forth over whether it was worth investing in Dallas Keuchel? It looks like we got our own Dallas Keuchel in house. If you consider the cost of the contract and years of control before free agency, no way you’d trade Dobnak for Keuchel right now. And I really like Keuchel. I’m not even sure I’d trade them if they were on the same contract. And if it was a long-term contract, definitely not. They are comparable now, and Keuchel isn’t getting any younger.

Yes, teams could figure him out and find a weakness, or he could make a few more errors in location and give up a few big hits every game, and settle in as a mid-rotation starter. That’s what usually happens. Remember the great early years we got from Carlos Silva and Scott Diamond. But I keep rubbing my eyes and he keeps doing it. And they didn’t have the lateral movement in opposite directions he has. He looks a lot more like a future Maeda or Hill to me than a future Diamond or Silva.

With Berrios, Maeda, Hill, Odorizzi, Dobnak, and Pineda, this rotation looks pretty solid, health permitting. I don’t know that any of those guys will be favored against a game one ace in the playoffs, but if the hitters get back to where they were last year, that might not matter.

Like a throwback Terry Ryan pitcher

The Twins used to love sinkerball pitchers who didn’t walk anyone – Joe Mays, Carlos Silva, Nick Blackburn. Derek Lowe is another name from the past we can use as a reference. I think Dobnak benefits because pitchers like this are out of favor which means he presents a different look.

Regarding staff ace, I think the Twins may have found one this offseason but I think it’s Maeda. He has a much longer track record of success.

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