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Sam Chinitz evaluates starting pitchers who gained velocity with their fastballs in 2020 in order to project fantasy baseball value for the 2021 MLB season.
The shortened 2020 season resulted in some small sample size related caveats surrounding analysis heading into 2021, but fastball velocity is largely immune from that issue. Fastball velocity is extremely quick to stabilize, and even a few pitches can provide fantasy managers with a reasonably clear understanding of a pitcher’s velocity.
Further supporting that notion is the fact that fastball velocity is remarkably sticky. Even without any pitch count qualifier, the R^2 of one year’s velocity to the next is a high 0.83.
That’s not to say that the analysis in this article doesn’t require any small sample size caveats. Metrics to evaluate fastball performance like xwOBA and swinging-strike rate require more than a few pitches to stabilize, and fantasy managers should consider that caveat when looking at changes in fastball velocity.
Methodology
Increased fastball velocity is an improvement in a vacuum, but it doesn’t always translate to improvements in results. To that end, the relationships between changes in fastball velocity and changes in a fastball’s xwOBA and swinging-strike rates were weak among the 286 pitchers sampled in 2020, though the relationship between velocity changes and swinging-strike rate changes was stronger.
That’s not a totally unexpected result given that velocity is only one factor that influences a pitch’s success (pitch location, movement, and arsenal-related factors like pitch sequencing and tunneling likely also influence performance), but it is somewhat surprising. With that in mind, I’ll focus specifically on pitchers who both saw their velocity and performance improve.
Biggest Gainers In Fastball Velocity In 2020
Below is a list of the 15 pitchers with the biggest gaps between their 2019 and 2020 fastball velocities. The table also includes the difference between each pitcher’s fastball’s 2019 and 2020 xwOBAs and swinging-strike rates.
| Name | Velocity Difference | xwOBA Difference | SwStr% Difference |
| Keynan Middleton | 3 | -0.188 | 1.53% |
| Erik Swanson | 2.9 | 0.062 | 1.17% |
| Drew Smyly* | 2.6 | -0.048 | 1.71% |
| Yusei Kikuchi* | 2.5 | -0.073 | 5.87% |
| Brad Boxberger* | 2.5 | -0.026 | -0.93% |
| Phil Maton | 2.5 | -0.116 | 11.25% |
| John Means* | 2.1 | -0.141 | 5.84% |
| Paul Fry | 2.1 | -0.083 | -1.88% |
| Josh Staumont | 2.1 | -0.102 | 10.33% |
| Kevin Ginkel | 2 | -0.004 | 0.53% |
| Sean Reid-Foley | 1.9 | -0.168 | 2.84% |
| Jordan Romano | 1.9 | -0.298 | 9.96% |
| Yu Darvish | 1.8 | -0.249 | 6.37% |
| Burch Smith | 1.8 | -0.154 | 2.24% |
The players with asterisks next to their names have been expanded on below. As mentioned above I’ve focused primarily on pitchers who paired their velocity increase with improved results, although the choice of which pitchers to focus on was generally subjective.
Most Interesting Fastball Velocity Risers
Drew Smyly
Smyly’s fastball packed some extra heat in 2020 with career highs in average and max exit velocities, but the pitch wasn’t the primary driver of his impressive 38% strikeout rate nor his strong .287 xwOBA. Although Smyly’s fastball’s .360 xwOBA in 2020 was a significant improvement over its poor .408 mark from 2019, the pitch had posted an xwOBA lower than .360 in each of Smyly’s two full seasons before 2019.
Smyly’s success in 2020 can largely be traced back to his curveball instead, which led his arsenal in xwOBA and swinging-strike rate while increasing its usage rate to 36%. It’s still encouraging to see Smyly’s increased velocity, and if he’s able to maintain that elevated velocity then Smyly may see even greater improvements in 2021, but it’s important to note that Smyly’s more powerful fastball was not the primary driver of his success in 2020, and fantasy managers should keep that in mind.
Yusei Kikuchi
Kikuchi looked like a new pitcher in 2020 with his FIP dropping from 5.71 in his rookie year to 3.30 last season, and an improved fastball played a significant role in that improvement. Kikuchi’s fastball was a leading contributor to his elevated swinging-strike rate with the pitch seeing its swinging-strike rate jump nearly six points from 2019 to 2020, though velocity was likely not the only factor leading to the pitch’s success.
In addition to the pitch’s 2.5 mph velocity increase, Kikuchi’s fastball got an additional two inches of rise in 2020, and the 29-year-old would likely be particularly prone to benefit from elevating the pitch more frequently in 2021 as a result -- at least from a swinging-strike perspective. Kikuchi’s fastball improved its contact quality as well, with the pitch’s xwOBAcon dropping from .407 in 2019 to .366 last season, although that’s slightly less intriguing given that pitchers tend to have less control over contact quality compared to their swinging-strike rates.
It’s worth noting that the structure of the 2020 season was likely especially beneficial for Kikuchi, who struggled to pitch through the length of the full 162 game season during his rookie season. Seattle’s adoption of a six-man rotation also provided Kikuchi with more rest between starts (closer to what the pitcher was used to in Japan), likely helping him maintain his elevated velocity. Still, the development of Kikuchi’s fastball in 2020 was extremely encouraging, and fantasy managers should keep that in mind heading into 2021 drafts.
John Means
Means is one of my favorite buy-low candidates for next season, and the 27-year-old’s improved fastball doesn’t hurt. Means saw his fastball jump just over two mph from 2019 last season, and a release point closer to home plate resulted in a more than three mph increase in the pitch’s perceived velocity.
Means saw his fastball results improve significantly as well with a near six-point jump in swinging-strike rate and a 141 point drop in xwOBA. Home runs were a problem for Means’ fastball as the pitch allowed five home runs, but only one of those homers came at a ballpark other than the homer-friendly Camden Yards and Sahlen Field (Buffalo), and Means’ 1.086 xwOBA on those five home runs was relatively low. Camden Yards isn’t going anywhere, but Means’ fastball’s surface-level results should improve in 2021, and fantasy managers should target the pitcher in drafts as a result.
Yu Darvish
Darvish’s fastball saw its usage rate drop to a career-low 15% in 2020, but the pitch was as effective ever with a career-high 96 mph average velocity and elite metrics across the board. It’s hard to overstate just how good Darvish’s fastball was in 2020; the pitch posted a sparkling .146 xwOBA that ranked third among fastballs (min. 25 PA) in 2020 along with a 19% swinging-strike that represents the second-best full-season mark from a starting pitcher since at least the start of the 2017 season.
That elevated swinging-strike rate didn’t show up in Darvish’s strikeout rate (which mirrored his 2019 mark at 31.3%), but it did help Darvish pitch in pitcher’s counts for a career-high 35% of his pitches*, contributing to his overall effectiveness. It’s hard to expect Darvish’s fastball to be so dominant again in 2021, but the 34-year-old should manage to carry over at least some of the improvements, and that should have fantasy managers excited heading into 2021.
Brad Boxberger
Boxberger didn’t see his performance improve as much as some of the other pitchers on the list, but his 2.5 mph increase in average fastball velocity is notable. Injuries (and possibly age) pushed Boxberger’s average fastball velocity down in each of the five seasons leading up to 2020, and his 92.5 mph average velocity in 2020 was his highest mark since 2016.
That Boxberger made it through the entire season with a velocity rebound and no major injuries bodes well for his value in 2021. Boxberger is an intriguing deep-league option for fantasy managers as a result, and the 32-year-old may be worth a flier in later rounds depending on his likely role in 2021.
*Darvish led off with a fastball in only 15% of his plate appearances this season, but the pitch’s dominance no doubt played a role in his ability to get ahead and stay ahead in counts.
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