Airing It Out: A Look at This October’s Fastball Velocities

In Game 6 of the ALCS, en route to clinching the American League pennant for the third time in five years, the Astros received quite the start from Luis Garcia. As a team hampered by rotation issues, issues only accentuated by the injury to Lance McCullers Jr. in the ALDS, Houston needed someone other than Framber Valdez to step up and perform. Non-Valdez starters had recorded just 12 measly outs in Games 2 through 4; in retrospect, the Astros were probably lucky to have come away with even one of those games.

After a brilliant Valdez start to put Houston up three-games-to-two, it was once again Garcia’s turn to get the ball. The team’s No. 3 starter during the regular season, he had been productive all year but exited Game 2 of the ALCS with an injury; Garcia’s fastball velocity in his second inning of work was down almost 4 mph relative to his first inning mark. On Friday, though, the script was completely flipped: Garcia was airing it out. After only throwing one 97 mph pitch the entire regular season, he recorded eight against Boston. His 5 2/3 shutout innings, allowing just one hit and one walk, made him the most valuable Houston player of the evening, with a +.308 WPA. That type of performance is a necessity if the Astros want to triumph over the Braves and win the World Series.

In the midst of his excellent outing, there was a lot of oohing and aahing over Garcia’s velocity. As ESPN’s Jeff Passan tweeted during the game, Garcia’s stuff was “ticking way, way, way up.” For those counting at home, that’s three “way”s, and deservedly so. Garcia threw the five fastest pitches of his career in Game 6; he has thrown the eight fastest pitches of his career all in the postseason (seven in Game 6, one against the Rays last year). The righty averaged just 93.3 mph on his four-seamer during the regular season, but in Game 6, he averaged 96.0. That average fastball velocity was 1.4 mph faster than his highest average in any other outing this season (94.6 mph, April 12). He was amped up.

But Garcia isn’t the only pitcher to see velocity gains in October, and that’s not a shock. Pitchers seeing maximum velocity gains from the regular season to the postseason happens every single year. In the playoffs, pitchers (especially starters) are expected to throw fewer innings, allowing them to reach back for a little extra if need be. Plus, I’m sure there is quite a bit of extra adrenaline pumping when pitching in October. Here are the 15 pitchers to record a higher fastball velocity on their fastest pitch in the playoffs than they did during the entire regular season:

A lot of these are marginal increases, with seven pitchers seeing a bump of 0.2 mph or less, but there are still some very interesting jumps here. Lance Lynn, for example, threw more fastballs than any other big league pitcher this season, and by a healthy margin at that. But he threw the 19th-hardest pitch of his career (out of more than 23,000 fastballs) in Game 1 of the ALDS. And Lynn’s teammate, Dylan Cease, eclipsed the century mark for the first time this season, throwing the hardest fastball of his career to Alex Bregman in Game 3 of that same series.

Garcia’s teammate and current Astros rotation anchor Valdez also threw the hardest pitch of his season (though it was “just” the third-hardest of his career) in Game 5 against the Red Sox. The Braves, meanwhile, only have one pitcher here: Dylan Lee, who only threw 12 pitches in two innings during the regular season and was added to the NLCS roster to replace Huascar Ynoa; he pitched the seventh and eighth innings in the Dodgers’ 11-2 Game 5 rout. Even still, he was up to 95.2 mph, though it’s possible he would’ve gotten there anyway had he thrown a full regular season.

This phenomenon isn’t unique to 2021. Eno Sarris wrote about postseason velocity bumps at The Athletic back in 2018. He analyzed how pitchers sit closer to their maximum fastball velocity much more often in the postseason than they do in the regular season. This matters when it comes to performance, too. In 2017, Rob Arthur and Greg Matthews wrote about how baseball’s “hot hand” is real for FiveThirtyEight. Their methodology focused on pitcher fastball velocity, and they noted how much it can matter in a short postseason series, where an excellent start or a clunker can have enormous implications for the outcome. In sum: Throwing harder in October might be due to adrenaline, but being able to do so may also indicate something about the type of performance a pitcher is about to deliver.

That’s why we should also look at the flip side of this coin: pitchers whose fastest pitch this postseason is markedly down compared to their regular season maximum. As you’ll see, there’s way more room to the downside than to the upside; some of these pitchers have been quite a bit away from their maximum velocities. Being far from your maximum, of course, is also dependent on plenty of other factors (the first that comes to mind for me is weather), but it remains interesting to break down:

Obviously, sample size plays a much larger role here, as pitchers who have fewer opportunities to hit their maximum velocity will be less likely to do so. That’s why, if we’re trying to evaluate potential pitcher success or failure from velocity, it’s probably better to look at their postseason versus regular season average, even though it is interesting to see where they are relative to their maximum. Here are the top- and bottom-five pitchers in average fastball velocity this postseason relative to their regular season average:

It’s many of the same names, with Valdez and Garcia again near the top of the list. If we focus on only Braves and Astros pitchers, this is the list:

Of the 24 pitchers here, only eight have failed to at least meet their average regular season fastball velocity so far in the postseason. And while that doesn’t necessarily mean you should worry if Dusty Baker or Brian Snitker brings one of these guys in, it’s worth noting that on average, every tick in fastball velocity is worth between a third to a half of a run per game in run suppression. Unsurprisingly, you’d rather have the guys who are throwing hard than the ones who may be showing signs of fatigue.

This can all change. As Arthur and Matthews found in their study, “the typical pitcher goes through 57 streaks in a season, jumping between hot and cold every 24 fastballs,” meaning that pitchers near the bottom of this list could end up seeing velocity gains in the World Series, and those at the top could see their fastballs fall off the table. But in a short series, you want to be absolutely certain that the pitcher coming into the game has his best stuff, as that could legitimately be the difference between going home empty handed or with the Commissioner’s Trophy. As Arthur himself recently tweeted, pitchers running hot or cold can impact game win probability by as much as 5-10%. With the World Series starting tonight, keep a close eye on the radar gun, as it may be the first indication of whether a pitcher is on his game or not. When he was pumping 97 in Game 6 of the ALCS, Luis Garcia certainly was.