Analyzing Fly Ball Metrics: Pitchers to Trust in 2021

Connelly evaluates fly-ball metrics from last season to pick out fantasy baseball starting pitcher risers, fallers and potential draft values for the 2021 MLB season.

Welcome back to some 2020-2021 offseason fantasy baseball analysis! I recently took a look at pitchers who could see a decrease in performance next season based on their fly-ball metrics from this season. Some of these metrics included home run-to-fly-ball ratio, fly-ball rate, and average launch angle.

To reiterate the value of this type of analysis, an increasingly important phenomenon for both pitchers and hitter over the past several seasons has been the Fly Ball Revolution, or the proclivity for hitters to actively try to hit the ball in the air in order to beat shifts and get higher-impact hits. Consequently, pitchers can generally avoid damaging contact if they can keep the ball on the ground.

For this article, I will take a deep dive into a few pitchers' batted-ball profiles from 2019 to 2020 to identify those who could see some positive regression in the 2021 season or maintain their solid production from this season. To be considered for this article, a pitcher needed to have at least 50 batted-ball events in both 2019 and 2020 (per Statcast).

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Blake Snell (SP, TB)

Blake Snell is a pitcher with a ton of promise from a fantasy perspective who has been inconsistent over the course of his career. Snell's 2019 33.3% strikeout rate was encouraging, but his 4.29 ERA, 4.7 IP/start, and IL stints (fractured toe, loose bodies in pitching elbow) were disappointing. On the other hand, 2020 was a great success; Snell went 4-2 with a 3.24 ERA, 1.20 WHIP, 31% strikeout rate, and some excellent batted-ball metrics. He also pitched a strong post season and nearly helped his team to a championship. How did Snell's batted-ball profile contribute to his success?

Snell seemed to trade soft contact for keeping the ball on the ground in 2020 compared to 2019. His average exit velocity stayed roughly the same (88.3 MPH in 2019, 87.8 MPH in 2020) and his hard-hit rate increased from 32% to 36.9%. Conversely, his average launch angle decreased a good deal (15 degrees in 2019, 6.6 degrees in 2020) and his FB rate dropped from 22.9% to 16.4%. The drop in launch angle could be attributed to solid location of all of Snell's off-speed pitches.

The relationship between Snell's batted-ball profile and his ERA over the past two seasons may suggest that a lower launch angle is more important than soft contact. However, his SIERA in 2019 (3.56) was almost identical to his SIERA in 2020 (3.57). This suggests that Snell's overall batted-ball profiles in both 2019 and 2020 were pretty stellar and that he got unlucky in 2019. He had pitched well in both 2019 and 2020, and his performance metrics caught up to reflect that in 2020.

Snell has put forth strong performances over the past several seasons in terms of his batted-ball profile and his strikeout rates. His FB metrics, while slightly different in 2020 compared to 2019, yielded strong expected results. Given the consistency of his expected performance over the past several seasons, I expect Snell to continue to be a strong fantasy pitcher. The only thing that could hinder his fantasy value is a continued lack of depth in his starts. Despite his skills, Snell averaged just 4.5 IP/start in 2020. Starters need to go at least five innings to be eligible for a win, so if manager Kevin Cash lets Snell pitch deeper into games, he could be a top fantasy starter in 2021.

Max Fried (SP, ATL)

Max Fried is just one of the Braves' many promising young starters, and 2019 was fantasy players' first opportunity to see him at the big-league level full-time. His numbers that season, while not shabby in any regard (17-6 record, 4.02 ERA, 1.33 WHIP, 24.6% strikeout rate), were not as exciting as anticipated. He did not disappoint in 2020, however, going 7-0 with a 2.25 ERA, a 1.09 WHIP, and a 22.3% strikeout rate. What about Fried's batted-ball metrics changed to allow for such a shift?

The key to Fried's success wasn't a change in fly balls allowed, but the damage (or lack thereof) allowed from those fly balls. Fried's average launch angle, while still quite low overall, actually rose slightly from 2019 to 2020 (4.3 degrees vs 6.4 degrees). Consequently, his FB rate rose slightly from 16.6% to 17.9%. In contrast, Fried's HR/FB rate drastically decreased from a poor 20.2% to an impressive 4.9%.

These seemingly contrasting metrics could be explained by a big drop in Fried's exit velocity and hard-hit rate. Fried's average exit velocity dropped from 89.2 MPH to 83.4 MPH and his hard-hit rate dropped from 39.1% to 23.8%. Both of these stats were in the 98th percentile of baseball. As I mentioned in my fly ball bust article, fly balls are not necessarily bad/damaging if they aren't hit hard. Further, Fried swapped some of his four-seam fastball usage (53.1% in 2019, 41.8% in 2020) for a sinker (3.5% in 2019, 10.1% in 2020), a pitch that should help him continue to keep the ball out of the air (-12-degree launch angle in 2020).

In sum, Fried didn't actually drop his FB rate or overall launch angle, but he did a much better job at avoiding damage on balls hit in the air. While he may not replicate his stellar ERA in 2021, I think the changes in his game will allow him to continue to succeed and be the valuable fantasy starter players had hoped for.

Tyler Glasnow (SP, TB)

As discussed above, Blake Snell's performance metrics coincided with his batted-ball metrics in a positive way in 2020. For his fellow rotation-mate Tyler Glasnow, the same relationship was found but in a negative manner. Glasnow had some very good numbers in some regards (5-1 record, 1.13 WHIP, 38.2% strikeout rate), but his 4.06 ERA was pedestrian and his FB metrics left much to be desired (as we will see). If this is the case, why do I have him in my potential risers article?

Before we answer that question, let's first take a look at Glasnow's 2020 batted-ball profile. He saw an increase in his average launch angle (10.5 degrees in 2019 vs 13.4 degrees in 2020) and his FB rate (18.6% in 2019 vs 25.6% in 2020). He also saw a huge jump in his HR/FB rate, from 8.5% in 2019 to 23.4% in 2020. The underlying culprit here could be how hard Glasnow got hit; his 90.4-MPH average exit velocity and 42.4% hard-hit rate were both in the bottom 20 percent of baseball. Given how hard he throws (96.9-MPH fastball, 82.4-MPH curveball), it makes sense that hitters could do some damage against him when hitting the ball in the air.

Now to answer the question of why do I think he can rebound in 2021. First, Glasnow strikes out a ton of hitters and doesn't allow many hits overall. That, combined with his excellent 3.04 SIERA from 2020, suggests that his batted-ball profile should have yielded better results than what he saw. Second, several of Glasnow's batted-ball metrics simply seemed to underperform compared to his career marks (HR/FB rate: 23.4% in 2020 vs 16.8% career; hard-hit rate: 42.4% in 2020 vs 36.1% career). It seems reasonable to think that those metrics could regress towards his career averages in 2021.

Glasnow has shown he has great stuff, is a top strikeout pitcher, and doesn't allow many hits. His batted-ball profile in 2020, while not great, stood in contrast to a strong SIERA. If some regression occurs in 2021, he should be a very effective fantasy starter.

Zac Gallen (SP, ARI)

This last pitcher, while he did have hype around him going into 2020, was not expected to be the pitcher he turned out to be. Zac Gallen fit into the Diamondbacks rotation as an exciting prospect behind newly-signed "ace" Madison Bumgarner, strikeout artist Robbie Ray, and healthy Luke Weaver. He ended up being the clear leader amongst those four, going 3-2 with a 2.75 ERA, a 1.11 WHIP, and a 28.2% strikeout rate. What encouraging signs stood out in Gallen's FB metrics?

There were positive signs all around for Gallen. For starters, his average launch angle decreased from 13.6 degrees to 12.4 degrees. Even better, his FB rate decreased greatly from 28.3% to 16%. In terms of hard contact, Gallen's 87-MPH average exit velocity (73rd percentile in baseball) was the same as it was in 2019 and his hard-hit rate decreased from 35.9% to 32.6% (78th percentile in baseball). The 25-year-old used four different pitches in his repertoire and did a good job locating all of them.

Simply put, Gallen showed once again that he has the makings of a solid starting pitcher. He located pitches well, avoided hard contact, kept the ball on the ground, struck hitters out, and pitched relatively deep into games (6 IP/start). He took positive steps from his rookie season, and there is no reason to think that he cannot continue to move in that direction in 2021.

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