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How vertical approach angle helps explain “sneaky” fastballs

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This new stat gives us a better understanding of why some otherwise unimpressive fastballs seem to be invisible

Minnesota Twins v Cleveland Indians
Twins rookie pitcher Joe Ryan
Photo by Ron Schwane/Getty Images

Debuting for an organization starved for exciting young pitching in recent years, right-hander Joe Ryan generated some buzz with his five September starts. Ryan’s fourth major league start, against the Chicago Cubs, included 11 strikeouts in 5 innings, the most in franchise history in an outing that long or shorter. That day, Ryan punched out the last 7 batters he faced, something that has only been done three times in the expansion era, by some really impressive names:

Though it was just five big league starts covering 26.2 innings with a 4.05 ERA, Ryan often looked dominant on the mound by striking out 30% and walking just 5% of the opposing batters he faced while holding them to a .168 batting average. His performance has given optimism – both in terms of on-field results and the eye test – that the Twins got the better of the Tampa Bay Rays in this trade and acquired an effective and controllable starting pitcher for a two-month rental designated hitter (Nelson Cruz).

Before Ryan’s debut, tall right-hander Bailey Ober forced his way into the Twins’ pitching picture last season when he consistently outperformed his raw stuff and prospect profile. Over 90.2 innings with the Twins, Ober delivered a 4.19 ERA, struck out more than a quarter (25.3%), and walked just 5% of the batters he faced. Ober’s rookie campaign makes it seem as though the Twins have developed a probable back-of-the-rotation starter out of a former 12th round draft choice.

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Even with the strong rookie campaigns and extensive (by today’s standards, anyway) track records of minor league success, the various public prospect evaluating outlets have expressed doubts about both pitchers having what it takes to stick as major league starters. Prior to last season, the prospect projections expected both pitchers to find major league roles in time, but those roles ranged from back-end starters to change of look relievers.

In both cases, the scouts’ doubts come from the two pitchers’ lack of traditionally imposing “stuff” and average-ish arsenals that are very reliant on four-seam fastballs. Ryan averaged 91.2 MPH on his four-seam fastball in the majors, which slotted into the 21st percentile among all pitchers. Ober ran his four-seam fastball a tick better at 92.3 MPH. While that represents a major increase from his 86-88 MPH minor league days, it was still only in the 33rd percentile.

Neither pitcher possesses devastating offspeed pitches. They both have the usual complement of breaking pitches and a changeup, but those secondaries grade out as average or below offerings per the public scouting reports.

Despite their lack of velocity, they both found success in their first trials in the big leagues by leaning heavily on their fastballs. Ryan used his four-seamer for more than 65% of his pitches, a rate that was 32nd-most of the 695 pitchers to throw at least 100 four-seamers last season. But among starting pitchers, Ryan’s rate of fastballs is clearly the highest of any pitcher. All the pitchers above and around him on the list are relievers. Ober’s 58% rate of four-seamers is not to the extreme of Ryan but still checked in at 101st on the list linked above, just inside the top 15% of all pitchers and again one of the highest rates among starters.

When they went to their fastball, they most frequently located them at or above the top of the strike zone. Ryan located 57.7% of his four-seamers in the highest five zones of the chart below:

baseballsavant.mlb.com

Ober took it several steps further and put 73.3% of his four-seamers in those zones:

baseballsavant.mlb.com

While the rest of the league allowed a .283 average, .518 slugging percentage, and .380 wOBA on four-seam fastballs clocked between 91 and 93 MPH last season, Ryan allowed .198/.362/.253 (BA/SLG/wOBA) and Ober allowed .251/.466/.322 with their four-seamers. In addition, both pitchers got surprisingly strong rates of swings and misses with that pitch type. Ober’s 24.8% four-seamer whiff rate ranked 183rd out of 628 pitchers to face 10 batters, and Ryan’s 20.3% rate ranked 341st on the same list.

In recent years, thanks to pitch tracking technologies, we’ve learned a lot from measuring other characteristics of pitches than their velocity. We know that fastballs with high spin rates and certain kinds of movement profiles can help them play above their velocity readings, especially for getting swings and misses.

But neither of those is the case with Ryan and Ober. Ryan averaged 2175 RPM on his fastball (34th percentile) and Ober’s average of 2177 RPM was in the 35th percentile. According to Statcast’s pitch movement leaderboard, Ober is in the middle of the pack in terms of vertical and horizontal movement and the same can be said for Ryan’s vertical movement. Ryan does benefit from horizontal movement that shows up in the top quartile.

It seems counterintuitive for these pitchers to be working so prominently up in the zone with traditionally below-average fastballs. It certainly goes against Bert Blyleven’s “downward plane” credo, but their results last season speak for themselves and it is clear that this approach is a deliberate strategy.

So why does this work for these two?

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Vertical approach angle (VAA) is a relatively new measurement that tells us the angle (in degrees) at which a pitch crosses home plate. You can think of it along the same lines as launch angle, which we have been using for a few years to describe the angle at which a batted ball leaves the bat after contact. If the launch angle is the angle at which the ball leaves home plate, VAA is the angle at which the pitch approaches home plate. The concept is explained simply in this video. Other useful primers include the introduction to this piece by Ethan Moore (who now works in R&D for the Twins) from 2020 and this Twitter thread and video from Ben Brewster of Tread Athletics.

While I recommend digesting the background info linked above, here’s a quick cliff note version that will help with the rest of my post here about Ryan and Ober.

Almost all pitches approach home plate on a negative angle, in part because of gravity, but also because the pitchers are throwing from an elevated mound. A pitch on a perfectly flat, zero-degree angle, thrown from the pitcher’s mound would likely end up over the catcher’s head. In order to locate a pitch within the accepted strike zone, pitchers have to throw the ball on a slight downward (i.e., negative) angle. Therefore, pitches that measure closer to zero degrees are described as having “flat” VAAs. Pitches with more negative VAAs are described as having “steep” VAAs.

The steepness of VAA varies based on a few different factors. Pitch type is one big factor. Four-seam fastballs tend to be the flattest pitches and typically measure between negative-4 and negative-7 degrees, while curveballs tend to be the steepest pitch types and mostly measure between negative-7 and negative-16 degrees. The various other pitch types fall somewhere in between.

Other important factors affecting the VAA of a pitch include a pitcher’s vertical release point (low release points tend to lead to flatter VAAs and vice versa) and extension (more extension tends to lead to flatter VAAs and vice versa). In fact, this short study by the University of Iowa baseball managers found that vertical release point and extension together can predict almost 95% of pitch VAA.

Moore’s work linked above found that VAA has a relationship with fastball performance, especially when linked with location. Simply, he found that fastballs with flatter VAAs perform better (especially in terms of getting swings and misses) when located up in and above the zone because they appear to “rise” much in the same manner as fastballs with high spin rates, and fastballs with steeper VAAs perform better when located down in the zone. This finding was explored in much greater depth by Alex Chamberlain for FanGraphs early last year.

That takeaway might not seem like a big deal — we’ve known for a long time that four-seamers (flatter) often play best up in the zone and sinkers and offspeed pitches (steeper) play best down. But being able to measure the VAA of pitches has helped us better understand outliers. By and large, VAA doesn’t have a ton of impact on pitch performance, except in the extremes. As always, everything in pitching is relative and it often pays to stand apart from the norms.

This is where Ryan and Ober come back into this. According to a public leaderboard derived from Statcast data and maintained by Chamberlain, the two Twins’ rookies have some of the flattest angle four-seamers in baseball. The league average VAA on four-seamers last season was -5.0 degrees. Ryan’s four-seamer averaged -4.2 degrees and was within the top 7% flattest angle four-seamers out of 804 pitchers listed on the board. Ober’s four-seamer averaged -4.4 degrees and was within the top 15% flattest.

This detail is a major part of what makes their otherwise below-average four-seamers remarkable and why they can work dominantly at the top of the zone, even though their velocity, spin rates, and vertical movement measurements might suggest they should not.

As should be expected given the findings noted above, Ryan and Ober’s flat VAAs are the result of low vertical release points and extension. Ryan released his pitches at 5.09 vertical feet on average, which was the 31st lowest vertical release point of 589 pitchers to throw at least 300 pitches last season. I wrote last season about Ober’s elite extension and low vertical release point. His vertical release was measured at 5.82 feet on average, 259th on the same list, but all the more unique given that he stands 6-foot-9.

Those flat VAAs, when coupled with long-limbed, deceptive deliveries make these four-seamers play like invisi-balls and miss a lot of bats, which this Twitter thread from Parker Hageman illustrates with video:

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It will be interesting to see how the scouting outlooks for Ryan and Ober are adjusted this winter after they’ve demonstrated some initial success as starters in the major leagues and the baseball industry continues to incorporate vertical approach angles into their evaluations. It remains unknown whether the unique fastballs alone will be enough for Ryan and Ober to dispel the doubts about their viability as starting pitchers and it’s worth noting that the top of Chamberlain’s leaderboard for flat angle fastballs is predominantly filled with relief pitchers.

While the bulk of pitchers with this unique trait may be relievers, there are some very successful starters — including Jacob deGrom, Gerrit Cole, Luis Castillo, and Corey Kluber — that have this trait. Of course, they all also have at least one dominant secondary offering, which is why the Twins’ development plans for Ryan and Ober undoubtedly will emphasize improving their offspeed pitches. We got a glimpse of what that meant for Ober last season when he added velocity to his slider as the season progressed.

The Twins are likely to give both pitchers every opportunity to prove they can’t be successful starters while having confidence that each has the floor of a useful, multi-inning reliever to fall back on. While these two pitchers becoming multi-inning relievers would not be the outcomes Twins fans are hoping for, they would still be a great return for former 7th and 12th round draft picks. For that, the Twins can thank their sneaky fastballs.


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