Let’s compare fastball velocity with wRC+.
It’s good to throw hard. Pitchers who throw higher velocity fastballs generally perform better than soft-tossers. There are exceptions, such as Kyle Hendricks and Zack Greinke, but flamethrowers often have an advantage. Included among the top ten highest velocity starting pitchers are Noah Syndergaard, Tyler Glasnow, Gerrit Cole, Walker Buehler, and Jacob deGrom.
Each starting pitcher’s average fastball velocity falls between 87.1-98.3 mph. Relievers have a similar range if you exclude outliers like Jordan Hicks, who averages 102.2 mph. MLB fastball averages cover roughly an 11 mph spread.
If faster equals better for pitchers, the inverse should also hold true for hitters. We should expect that when batters face higher velocity pitching, they should see a decrease in performance.
Given that batters face lots of pitchers, the range of average fastball velo against is much smaller than fastball velo for pitchers. The average fastball velo against ranges 91.8-93.9 mph. That two mph spread for qualified hitters is still rather large considering how many different pitchers a batter must face.
Using wRC+ as a measure of overall offensive performance, we can compare batters’ success with how hard opposing pitchers throw.
There is a lot to unpack with this chart, but no correlation between velo and wRC+. The correlation score is just 0.02, which is basically nothing at all.
At the bottom end of the velo-against scale is Joc Pederson (91.8), followed by Max Muncy (92.0). It appears that the Dodgers have faced a lot of soft-tossers this year, especially since Cody Bellinger (92.3) is also in the bottom-ten. Additionally, the Angels have four players in the bottom ten: David Fletcher, Albert Pujols, Mike Trout, and Kole Calhoun.
At the other end of the spectrum, Juan Soto has seen the hardest fastballs in baseball at 93.9 mph. He’s followed by Manny Machado with 93.8 and three players at 93.7: Bryce Harper, Joey Gallo, and Jonathan Schoop.
This does not mean that velocity has no effect on hitters. We talk about “small sample size” all the time, but in this case the sample is probably too large and too varied. Batters see a lot of fastballs of all different shapes and sizes. Their average fastball velo against is too narrow a range to see any noticeable difference. If we measured how batters fare against all 98 mph fastballs compared to 90 mph, we’d probably see a relevant distinction.
There are some big names at the top and bottom of the velo against list, but what about percentage of fastballs? Is there any connection between performance and how many fastballs a batter sees?
Nope! This yields a correlation score of -0.11, which is next-to-nothing. What this chart does tell us is that there are a few players with known weaknesses. Marwin González and his 77 wRC+ has faced a lower percentage of fastballs than anyone in baseball this year, as we explored in further detail last week.
Conversely, Yasiel Puig (72 wRC+) and Lorenzo Cain (81 wRC+) have struggled while seeing more fastballs than anyone else. Just as with González, it appears that the scouting reports on what these hitters can and can’t hit has circulated around the league.
However, the biggest wRC+ outliers are in the middle of the chart. Bellinger leads MLB with a 227 wRC+, and has seen fastballs 52.3 percent of the time. This is scantly above the league average of 52.1 percent. The worst qualified hitters have been Chris Owings and Jackie Bradley, Jr., sporting 20 and 21 wRC+ while seeing 53.4 and 51.6 percent fastballs. In these cases, it doesn’t matter how many fastballs pitchers throw; they can’t get Bellinger out, while Owings and Bradley, Jr. are easily retired.
If individual batters don’t show a performance difference with fastball velo-against or percentage, teams certainly won’t either. Nevertheless, there’s always something interesting to find in the data. (The following charts use teams’ position player stats only, excluding pitchers batting.)
As expected, the correlation of -0.17 between velo-against and wRC+ means nothing. We do see some relatively large discrepancies in velo-against though. 27 teams see fastballs 92.6-93.3 mph. As intimated above, The Dodgers and Angels at 92.2 and 92.4 mph have seen significantly slower fastballs on average. The Nationals face the hardest throwers in baseball with 93.5 mph velo-against.
Now let’s look at team fastball against percentage.
This time, it’s an insignificant -0.14 correlation. There’s one major outlier all the way at the left. For whatever reason, the Rays are the only team in baseball that see fastballs fewer than 50 percent of all pitches. At 48.7 percent, they’re two points below the league average of 52.7 percent.
Did we find what we expected with the data? Not really, but we didn’t disprove anything either. Sometimes it’s good to just shake up some stats and see what comes out, even if it’s not what we were originally looking for.
Daniel R. Epstein is an elementary special education teacher and president of the Somerset County Education Association. In addition to BtBS, he writes at www.OffTheBenchBaseball.com. Tweets @depstein1983