Throwing by the Numbers: A closer look at the impact of fastball velocity

By Nic Osanic

In my previous article, we discussed the importance of fastball location and how pitching in the high and low portions of the strike zone can yield dramatically different results. One of the strongest examples of this was shown through Gerrit Cole. In Pittsburgh, Cole was a good starting pitcher with elite pitch potential (he could touch 100 mph on his fastball) but below average swing and miss results. This resulted in a few great seasons but also a few league-average seasons.

After being traded to Houston, Cole made better use of his elite pitches by throwing them more, and in areas where they were more effective. There were other technicalities at play in this scenario, but essentially, Cole’s new data-driven approach turned him into arguably the best pitcher in baseball. If you still need convincing on the power of proper pitch selection and location, here is a breakdown of the best player of the 21st century – Mike Trout.

Attacking Mike Trout (and surviving)

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Mike Trout is a true generational player. There is nobody in the game on the same level as him right now, and by the end of his career, he could be the best to ever play. With that being said, everyone has a weakness no matter how small it may be. In the case of Trout, he is no exception.

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Trout may be the best player on the Earth, but with the right approach, his bat can be somewhat silenced. In the last five years (Statcast era), Mike Trout has consistently destroyed every type of breaking ball, offspeed pitch, and low fastball thrown his way. All of these pitch types had an average exit velocity of 89.5 mph or above. However, there is hope with the high stuff. High 4-Seam fastballs are not hit as hard as other pitches and suffer less damage when contacted as shown by his xwOBA (expected weighted On-Base Average) on contact. Unsurprisingly though, Trout’s xwOBA on contact is well above league average for high 4-Seam fastballs and his swinging strike rate is well below the normal rate of 13.34%. Introduce a little movement to these high fastballs and all of a sudden, Trout looks a little less intimidating.

On 53 high 2-Seam fastballs or sinkers (similar movement profiles make it hard for Statcast to distinguish the two) hit in play during the last 5 seasons, Trout has yet to produce more damage than a single. On these pitches, he has gone 11-52 (one at-bat was a sacrifice fly and therefore not counted as an actual at-bat) which has resulted in a .212 batting average, .261 xwOBA on contact, and 0 home runs. His exit velocity on the high 2-Seamers and sinkers is 76.6 mph which is the lowest of all the pitch types he’s faced during this span. His 4.7% swinging strike rate is not ideal but since it is Mike Trout, the goal should be to just get him out instead of striking him out.

For Trout’s career (before Statcast and xwOBA were invented), he is hitting .243 with 2 home runs on 117 high 2-Seamers and sinkers hit in play. Over the course of a full season (in a full healthy season Trout puts around 400 balls in play), his home run total would average out around 7 per year if thrown nothing but high 2-Seam fastballs and sinkers. Obviously, Trout would improve if he only faced high 2-Seam fastballs and sinkers. but the point is that proper pitch selection and location can significantly impact even the greatest of hitters.

If high 2-Seam fastballs and sinkers work against Trout, do they work well against everyone else?

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The answer is it depends. Although high sinkers and 2-Seamers generate weaker quality of contact on average compared to every pitch type other than splitters and changeups, they also produce fewer swinging strikes. In this era of baseball, a swinging strike is the optimal outcome for a given pitch as the batter cannot reach base safely or advance any baserunners if he does not make contact with the ball. 

In theory, if every pitch type was thrown the same amount of times and a certain pitch had a low swinging strike rate, a higher percentage of its total outcomes will result in a ball in play. This means that low swinging strike rate pitches will lead to more balls in play and thus, a higher total quantity of baserunners. This is why pitchers like Gerrit Cole can get better results by throwing high fastballs over sinkers despite their home run and hard contact rates increasing (fewer baserunners allowed results in fewer runs allowed when hard contact finally does happen).

In the end, high sinkers and 2-Seamers are effective if your goal is to induce weaker contact (collective .349 xwOBACON). However, they also reduce the probability of attaining the optimal outcome of a swinging strike (collective 7.73% swinging strike rate). When facing a top-tier hitter such as Mike Trout, minimizing the damage and playing for weak contact (since he will likely hit any pitch you throw at him anyways) is a good strategy but pitching that way for an entire season will likely catch up with you as it leads an increase in baserunners. 

Since we now know that a swinging strike is the optimal outcome of a given pitch, let’s look at the top contributing factor to generating swinging strikes for fastballs – velocity.

Effect of velocity on high fastballs vs low fastballs

Before examining the full impact of velocity, let’s look at the starters and relievers with the best high 4-Seam fastballs during the 2019 season:

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When we look at the pitchers on these lists, we can expect to see some hard-throwers.

Gerrit Cole, Nathan Eovaldi, Carlos Estevez, Josh James, and Edwin Diaz all averaged over 97.0 mph on their fastball and many others averaged just below that. On the other hand, pitchers like Colin Poche, Jake Odorizzi, Tyler Clippard, Tim Hill, and Trevor Williams had great success despite averaging less than 93 mph on their 4-Seam fastballs. In fact, Brent Suter of the Milwaukee Brewers – who threw his 4-Seam fastball high nearly 50% of the time – had a tremendous amount of success for someone who only averaged 87.5 mph.

This shows that velocity is not necessarily the be-all and end-all to fastball success. There are a few other factors which can help make up for a lack of velocity. To find out just how much impact velocity has, I took every high 4-Seam fastball thrown between 2017 and 2019 and found its swing & miss percentage at 5 mph intervals. Here are the results:

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From this graphic, it is clear that 4-Seam fastball velocity matters quite a lot when thrown over the high portion of the plate. A high 4-Seam fastball thrown at 100+ mph is about 3-times more likely to generate a whiff than one thrown below 85 mph. In fact, the slider – widely thought as the hardest pitch to hit – had a swing & miss rate of 21.02% when thrown over the low portion of the plate from 2017-19. This means that a 100+ mph fastball thrown up in the zone is comparable to the dominance of a low slider. Now that we have seen what a high 4-Seam fastball is capable of at different velocities, we should probably check out how it compares to a low 4-Seamer:

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Similarly to the high 4-Seamer, swing & miss rates also increase with velocity on low pitches. However, these increases are not nearly as dramatic. Another takeaway from this comparison is that at each velocity interval, high fastballs generate 3-4 times as many swinging strikes as low ones. Also worth noting is that high 4-Seam fastballs thrown under 85 mph statistically generate more swinging strikes than low 4-Seam fastballs thrown above 100 mph.

After seeing the comparison between pitches that are low at 100 mph and high at 85 mph, I decided to take it a step further and see if this still holds when position players throw high over the plate.

Does Fastball Velocity and Location Matter for Position Players?

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The biggest takeaway here is that when throwing a high 4-Seam fastball, position players still nearly manage to generate the same percentage of swinging strikes as a low 100 mph fastball. As expected, position players generate fewer swinging strikes compared to the average pitcher for both low and high 4-Seam fastballs. This is likely because the average 4-Seam fastball thrown by a position player only clocked out at 78.9 mph on the radar gun. So what happens when we take all the fastballs thrown by position players that are over 85 mph?

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With a whiff rate of 7.59% on high 4-Seam fastballs, position players actually averaged more swinging strikes up over the plate than Major League pitchers such as Jordan Zimmerman (6.8%), Kyle Freeland (6.3%) Kyle Gibson (5.8%), Matt Harvey (6.5%), Mike Leake (6.2%), Michael Wacha (7.4%), and surprisingly, Mike Foltynewicz (7.3%) in 2019. For fun, let’s have a look at some of the position players who have had the most recent success.

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These “pitchers” all have a few things in common, albeit in a very small sample size. First, they all border 90 mph on their 4-Seam fastballs, and second, they have all had success using this pitch high in the zone.

Here is one of Russell Martin’s best outings from last season:

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In this game, Martin did a great job of elevating his fastball. He was pretty lucky with the first batter as Caleb Joseph hit a pop-up on a fastball right in his wheelhouse. However, he was then able to elevate his fastball against both Christian Walker and Jarrod Dyson. This resulted in a swinging strikeout and another weakly hit pop-up. Although one could argue that retiring Caleb Joseph, Christian Walker, and Jarrod Dyson is not the most impressive of feats, here is a comparison between former Arizona Diamondbacks’ superstar Paul Goldschmidt and his replacement, Christian Walker, in 2019:

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Goldschmidt had a slight edge over Walker but there is no doubt that Walker was still a great hitter in 2019. The fact that Martin threw him four high fastballs and got him to whiff on two of them shows just how dominant the high 4-Seam fastball can be. It is possible that Walker was not trying his hardest but that is likely not the case since facing a position player on the mound is a great opportunity to improve statlines and these statlines determine the worth of future contracts.

Conclusion

In this article, we examined the impact of velocity on high fastballs vs low fastballs. After breaking down each pitch into 5 mph intervals, we found that at every interval, high fastballs were 3-times more likely to generate a swinging strike than low fastballs. We also found that high fastballs thrown at 85 mph were more effective than low fastballs thrown at 100 mph. Taking it a step further, we saw how position players can be surprisingly competent against quality batters when pitching up in the zone despite their lack of “pure stuff.” These findings were definitely unanticipated but make sense given the MLB’s recent year-to-year increases in strikeouts (trend of more high fastballs thrown + increase in average fastball velocity = more strikeouts). 

With that being said, the importance of fastball velocity has been known for a while by the industry and is nothing new. However, the next article will explore the newest pitching metrics and techniques that can influence the success of each pitcher such as spin rate, active spin rate, spin axis, and pitch movement. These terms are relatively new in the baseball community but can often be associated with the unusual pitching breakouts we see every year. If you have enjoyed this article series so far, you will not want to miss the next one.

 

Statistics retrieved from Baseball Reference, Baseball Savant (Statcast), Fangraphs, and MLB.com

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