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How spin led the Twins out of the pitching wilderness - Part 2

Optimizing for fastball spin traits has played a key role in Minnesota’s pitching improvement

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Minnesota Twins v Detroit Tigers Photo by Duane Burleson/Getty Images

Today I’m continuing my look into how the Twins have turned pitching from the organization’s most critical flaw to a strength. Before Derek Falvey and Thad Levine took charge, the Twins had fallen behind the times in their approach to pitching. Those two leaders, plus manager Rocco Baldelli and pitching coach Wes Johnson, have overseen a major strategic shift on the mound. It heavily emphasizes individual player’s strengths, following data-driven insights, and squeezing value out of how pitches spin. Part 1 focused on how they’ve successfully applied this philosophy for breaking pitches.

Today, I’m going to look at how the Twins have used this approach to make the most of their pitchers’ fastballs.

The Context

Minnesota’s fastballs were some of the worst in baseball 2011-2016. Underneath that were two issues. First, the average Major League fastball velocity steadily increased while Minnesota’s stayed mostly the same. This caused the Twins to rank in the bottom third in fastball velocity every season from 2011 to 2016. Second, many clubs were beginning to throw fewer fastballs in exchange for more breaking balls, yet Minnesota continued to throw fastballs at some of the highest rates in the Major Leagues.

By 2016, the last season before Falvey and Levine came aboard, hitters produced a .307 / .377 / .523 line against Twins’ fastballs. The damage done against them worked out to .384 wOBA, a number that was equaled or bested by only fourteen qualified hitters that season. The chart below illustrates these issues:

In the four completed seasons since, Twins fastballs have allowed no higher than .359 wOBA, with the best season being .331 wOBA allowed in 2019. Relative to the rest of the league, Minnesota’s fastballs have climbed the standings, too. By pitch type linear weights, Twins fastballs improved to 17th in 2017 and were 7th-best in 2019.

So, what has been behind Minnesota’s fastball improvement?

Technology enabled insights

The implementation of Statcast technology in all Major League stadiums in 2015 and the widespread usage of high-speed cameras and other tracking devices has enabled an explosion of new data, information, and knowledge across the game.

In particular, we now have much improved ability to measure and subsequently derive insights from data points like release points, vertical and horizontal movement, spin rate, spin axis, and active spin (also called spin efficiency) for pitches. One of the key research areas advanced by this new tracking technology has been understanding the effects of how the baseball spins on how it moves, especially for fastballs.

Pitchers have long known that spinning the baseball in different ways could create different types of movement but before these advanced tracking technologies much of that understanding was limited to various types of off-speed and breaking pitches. Without making you read a detailed physics lesson suffice it to say that spin causes the baseball to experience Magnus force. As the link here explains, this effect and/or force is largely responsible for the amount of curve or “break” the baseball experiences as it is traveling to the catcher.

Think of the topspin used to throw a curveball. In earlier days curveballs were often called “drop-balls” because of how the pitch appeared to move on its way to home plate. The topspin enables gravity to impact the ball more, making it move downward quickly.

Contrast the top spin applied to a curveball with the back spin of throwing a four-seam fastball. Most of us who played youth baseball can probably remember being coached to grip the ball with two fingers across the baseball’s wide seams in order to throw the ball straight.

Pitcher or not, that grip is the best way to throw the ball with little movement. But little movement isn’t the same as no movement and there can be significant variation in how a four-seamer moves depending on the individual who throws it.

Some of the most important learnings of the Statcast era thus far have been understanding the effects of spin on how fastballs move. All pitches move downward between the mound and plate because of the effects of gravity. Whereas the topspin of a curveball works with gravity to create more downward movement, the backspin of a fastball works against gravity, muting some of the downward effects on the pitch. The faster a fastball spins (called spin rate), the more that downward force is counteracted, and the less the ball moves downward on its way to its target.

Here’s an example, which goes into much more depth than I will here. For simplicity, let’s say a four-seam fastball pitch is thrown 92 mph with a spin rate of 2400 revolutions per minute (RPM). This would generally be considered a high spin rate for a major league pitcher. Another pitch is thrown at 92 mph but with a spin rate of 1800 RPM.

Controlling for other variables like release point and location, the 600 RPM difference between the fastest and slowest spin rates can result in the faster spinning pitch crossing home plate about 7 centimeters above the lower spin pitch. This visual from Driveline Baseball illustrates the point:

Via Driveline Baseball: Link

That might not seem like much but consider it’s about the width of a major league baseball. At 90+ miles per hour 7 centimeters makes all the difference in the world to a batter trying to connect the bat with the ball.

Insights applied

We’ve long known these phenomena existed. Pitchers have been described as having “sneaky” and “heavy” fastballs for a long time. The technology we have today gives us the ability to accurately measure why.

The overly simplistic upshot of this is that, to the batter, high-spin fastballs appear to “rise” and low spin fastballs appear to “sink” relative to average spin fastballs. This explains why four-seam fastballs (which spin faster) tend to stay straight while two-seam fastballs (lower spin) tend to move.

As can be inferred from the example I gave above and is made clear here, fastballs with higher spin rates (i.e., the “sneaky” ones), even at the same velocity, tend to get more swings and misses and fly balls as batters usually swing underneath them. Conversely, fastballs with lower spin rates (i.e., the “heavy” ones) tend to get fewer swings and misses, but more ground balls as batters swing above them.

Both high spin and low spin can be advantageous for a pitcher if properly deployed.

Naturally, the high velocity fastballs with high spin rates have gotten a lot of attention in recent years. Everyone likes to see elevated 100 mph heaters blowing by batters. But that combination is scarce and the competition for pitchers with those characteristics is stiff and expensive (see Gerrit Cole, Yankees).

In this era of pitching for strikeouts, all teams will do what they can to acquire and develop high-velocity, high-spin fastballs. But there are many more opportunities to find competitive advantage by making the most of an individual pitcher’s innate spin characteristics, especially at lower velocities.

The New Twins Way

Minnesota has focused on using analytics and new ideas to optimize for and improve individual player strengths. Falvey made it clear this would be the approach when he took over the Twins baseball operations. Pitching coach Wes Johnson believes the same, saying “I believe it’s our job as a coach, and this is my philosophy, to find what a guy does really well and try to find a way to get him to do that more, as opposed to finding what he does bad and exploiting that and telling him he’s got to get better.”

To implement this vision, Falvey hasn’t shied away from taking some risk with new ideas — in fact, he sees it as crucial for being successful. “If we’re doing it the same as everyone else, by definition that’s league average,” Falvey said. “If we do things in a league-average way, we shouldn’t expect to be better than league average as a team, so in my mind, we have to be open to new ideas.”

Hiring Johnson straight from the college ranks is an example. His unconventional background for a major league coach necessitated a focus on exploring all options to develop raw talent. Knowing that he was unlikely to recruit top draft prospects when he was at small colleges, Johnson used his willingness to study and learn things like analytics, the latest technology, and biomechanics to squeeze everything he could out of the talent he had.

What that means in practice is different for each pitcher, as Johnson explained in 2019. “I’ve been asked that question: ‘What’s your pitching philosophy?’ Well, I’ve got one for Mike Pineda. I’ve got a completely different one for Martín Pérez or Kyle Gibson or Jake Odorizzi. Because their bodies work different, their stuff plays different, they need different things in the training room.”

This mindset makes him a near perfect fit for a franchise like the Twins given its place in the market and Falvey’s vision. The Twins need to find and exploit competitive advantages wherever they can get them.

Optimizing for spin

While the team has had some success adding velocity under Johnson (especially in 2019), one of the clearest ways the club has changed has been putting the new spin knowledge to work to adjust the types of fastball their pitchers threw. Consistent with baseball’s overall philosophy shift to pitching to avoid contact, but also to make the most of its pitchers’ strengths, Minnesota has decreased its reliance on sinking fastballs. In part 1, I pointed out the team had thrown significantly more breaking balls, at the expense of fastballs, in recent seasons. More granularly, those breakers have come mostly at the expense of sinkers and two-seamers:

Focus on the grey line in the chart. As a fraction of total pitches the Twins have thrown far fewer sinking fastballs in each of the past three seasons.

Whereas sinking fastballs and four-seam fastballs (yellow) were used about equally in 2017 (29%-30%), there is a clear split between them after that. In 2020, Minnesota threw 29.5% four-seamers and just 13.2% sinkers and two-seamers. Back in 2017, Minnesota had thrown the second-most sinking fastballs in baseball. In 2020, they threw only the 21st most.

In addition to the pitch type change the club also adjusted how the team’s pitchers located their fastballs to maximize the advantage of their different spin characteristics. The chart below illustrates the average vertical location of Twins’ fastball types when they crossed home plate over the past six seasons:

One of the first team-level adjustments made in 2017 was to throw faster-spinning four-seam fastballs to higher spots. Similarly, the club also started throwing their slower-spinning sinkers and two-seam fastballs to lower spots in 2018.

On the left side of the chart you can see the different pitch types had been located at more similar heights in 2015-2016. After, it is clear there was an intentional shift made to increase the separation between them and take fuller advantage of how those respective pitch types tend to move.

This change has had positive impacts. On four-seamers, the elevated location has helped yield more strikeouts. Twins four-seam fastballs had a 13.3% strikeout rate in 2016, the lowest in baseball. In 2017 that increased to 17.2%, before increasing again in each of the last three seasons. Last season that rate was 24.9% and ranked 7th.

Another added (and somewhat hidden) benefit has been an increased rate of harmless infield popups. The Twins rate of infield fly balls was 8.7% (22nd) in 2016 and has been 11.7% (4th) and 12.3% (3rd) the past two seasons.

Throwing fewer sinking fastballs and locating the ones they do throw nearer the ground has also paid off.

While sinking fastballs tend to yield less swing and miss than their four-seam counterparts, Minnesota has been able to get more strikeouts with sinkers and two-seamers after lowering their sights. The Twins’ strikeout rate for these pitches was 8.1% in 2015, the lowest in baseball. In 2019 and 2020, it was around 14% and ranked in the middle of the pack.

The new lower average location is one of the lowest in the game (t-4th lowest in 2020) and has yielded more ground balls. The average launch angle allowed by Twins sinking fastballs in 2017 was 10 degrees. Since, that angle has decreased to 3, 2, and 1 degrees in the last three seasons, respectively. As a result, the weighted on base average allowed by these pitches has improved from .374 in 2016 (t-27th) to .333 last season (10th).

Of course, for those changes to show up at the team level, individual players have to execute new plans. In some cases, that has meant adjustments for long-time Twins. In other cases, it has meant new faces being acquired.

Fastball adjustments

In part 1, I broke down Tyler Duffey’s 2019 adjustments to heavily emphasize his breaking ball. But that wasn’t the only adjustment he made. He also changed his fastball usage from a mix of four-seamers and sinkers to exclusively throwing four-seamers, mostly up. Duffey told Fangraphs’ David Laurila in 2019, “I’ve gone pretty much strictly to four-seams, which has created a lot of useful movement that plays up in the zone.

It’s an example of the Twins optimizing a pitcher’s strengths. Duffey has slightly above average spin rates on his fastballs. That spin helped his four seamer play up but was actually a hindrance to his sinker. By scrapping the sinker, Duffey emphasized what he does best and gave himself a chance for more swings and misses. He replaced a pitch that generated a roughly 10% whiff rate (sinker) with one that generates upwards of 30% whiffs (four-seamer). In 81.2 innings the past two seasons with this approach, Duffey has pitched to a 2.31 ERA, 2.91 FIP, batters have hit just .188 against him, and his 1.9 fWAR ranks 13th amongst all major league relievers.

The understated Cody Stashak is another example. As a 6’2, 180 pound, right-handed reliever that relies primarily on a four-seam fastball and slider, Stashak doesn’t stand out in traditional ways. His fastball has averaged just under 92 miles per hour in his two MLB seasons.

But Stashak is one of those guys whose fastball is “sneaky,” despite it’s below average velocity. Behind the deception of his fastball is spin that generates about three more inches of “rise” movement than the average fastball at his velocity and release point. Last season, Stashak had the 9th-most fastball rise compared to average of any qualified pitcher.

To take better advantage of this unique trait, the Twins have encouraged Stashak to work his fastball higher in and above the zone. As a rookie in 2019 his fastball crossed home plate at 2.64 vertical feet. In 2020 that increased to 2.91 vertical feet, resulting in Stashak’s strikeout rate increasing to 29.8% and his Statcast derived expected statistics improving across the board.

There could be some small sample size issues at play for a pitcher that has thrown just 40 career innings but it seems clear the Twins have identified an optimal approach for Stashak.

Fastball acquisitions

On the acquisition side of things, Minnesota has made several moves in recent seasons to bring on pitchers with “sneaky” fastball characteristics, often for minimal expense. While the Gerrit Cole’s of the baseball world attract $324-million dollar contacts, there are bargains to be had with high spin fastballs at lower velocities.

Left-handers Rich Hill and Caleb Thielbar are two good examples. Each was brought on ahead of the 2020 season due in large part to their shared traits of high-spin elevated fastballs thrown from high arm slots, despite well below average velocity.

In Hill’s case, he’s regularly been in the top quartile for fastball spin since making his return to starting rotations in 2015. He’s not ranked higher than the 21st percentile for fastball velocity in that span. Nonetheless, Hill has leaned hard on his four-seamer (50.8% of his pitches) and has rewarded his teams with just over 500 innings of 2.92 ERA / 3.48 FIP ball, in which he held batters to a .205 collective average, and struck out 28.6% of the batters he faced. The fastball has allowed just a .206 / .273 / .399 composite line (.289 wOBA). Despite an offseason elbow surgery that robbed him of some of the already limited velocity he did possess, the 40-year old Hill gave Minnesota 3.03 ERA over 8 starts in 2020.

Hill is, in some ways, a blueprint for Thielbar. Both were nearly pushed out of the game completely by injury and found their way back to the big leagues by getting healthy and then uncovering and committing to what they do best on the mound. In Thielbar’s case, he was a decent middle reliever for the Twins from 2013 to 2015, giving 98.2 innings of 2.74 ERA / 3.36 FIP pitching before minor arm injuries and ineffectiveness prevented him pitching in the majors again until 2020.

In between, Thielbar bounced between minor league teams and independent ball while searching for answers. In his first Major League stint, Thielbar threw both types of fastballs and relied primarily on a slider as his breaking ball. In the five years since, he’s found answers in some measure thanks to spin data. In 2020 Thielbar returned to the big leagues as primarily a four-seam fastball-curveball pitcher.

While his fastball only averaged 89.8 mph (9th percentile) in 2020, Thielbar used it heavily (54.4%) and it’s 2421 average RPM ranked in the 83rd percentile. That spin enabled the pitch to get 2.9 more inches of rise than average pitches in his velocity and release point range.

Hitters hit just .213 against the pitch, averaging only 84.9 mph average exit velocity, while swinging and missing 28.7% of the time it was thrown. Many of those swings and misses looked like this:

This new weapon, along with a reworked curveball, enabled Thielbar to a 2.25 ERA / 2.34 FIP season and the best strikeout rate (26.8%) of his career in 2020. More than that, it also paid off with a guaranteed contract with the Twins for 2021.

Hill and Thielbar are just two examples of high spin fastball acquisitions from a list that also includes Jake Odorizzi (61st percentile when acquired in 2017), Tyler Clippard (62nd, 2020), Devin Smeltzer (76th, 2020), and Jorge Alcala (76th, 2020).

The Twins implementation of this new approach isn’t limited to high-spin, elevated fastballs, however. The team has also made some additions with unique low spin fastballs — Randy Dobnak and his sinker chief among them. Dobnak’s improbable story has been well documented and much of his success can be attributed to that sinking fastball that has one of the slowest spin rates in baseball (4th percentile).

Dobnak might be the example that got the most attention for his low spin fastball, but Michael Pineda (3rd percentile) is another addition in recent seasons that shares the trait. On the internal development side, the Twins’ low spin list also includes José Berríos (25th) and Taylor Rogers (19th).

The Results

In the end, pitching is a complex series of interactions between batter and pitcher, and each subsequent pitch is in some measure dependent on what has happened in the pitches before. Which pitch types were thrown. Where they were thrown. How they moved. Hall of Famer Warren Spahn is often attributed the quote, “Hitting is timing. Pitching is upsetting timing.”

Spin data has armed smart franchises and pitchers with another tool to upset timing and Minnesota has been making the most of it in Falvey’s tenure.

If you combine the last four seasons (2017-2020), Minnesota fastballs have allowed a .276 / .354 / .454 triple slash line that rolls up to .347 wOBA. That line is almost identical to the league average batter production against fastballs over the same period — .272 / .352 / .460 and .348 wOBA — and a significant improvement over the six years prior.

This isn’t a story of Minnesota suddenly wielding dominant fastballs. But it is a story of them finally wielding respectable fastballs thrown within a strategic approach that best positions them to be successful.

But pitching is relative. Fastballs and breaking balls can make each other better when they are deployed in ways that maximize their effectiveness. Using technology to develop and better utilize the spin characteristics of different pitch pairings has been the final piece of the puzzle for fixing Minnesota’s pitching over the past 4 years. I’ll break that down in Part 3.

(Data throughout this post was sourced from and

John is a contributor to Twinkie Town with an emphasis on analytics. He is a lifelong Twins fan and former college pitcher. You can follow him on Twitter @JohnFoley_21.