Why Are We Throwing Fastballs? The Numbers Behind Them In College

Mason McRae
6 min readOct 31, 2022

College baseball is routinely a few years behind every advancement in the baseball world, and that’s not a knock on the college game. The coaches that are ahead tend to get scooped up before they have a chance to influence the college game. The Cardinals hired Dusty Blake away from Duke, the Pirates hired Josh Hopper away from Dallas Baptist, and the Twins hired Wes Johnson away from Arkansas. It’s hard for college to change when the ones empowering the change leave. Fortunately, we’ve gotten to the point where the players want to learn more about the numbers, and head coaches — including those at the helm of programs that have won for multiple decades — are starting to look for coaches at least open to it.

College as a whole has started moving in the right direction. Fastball usage has dropped roughly 6% since 2019, but it’s still way behind the pro game. This past college season, 56.2% of pitches thrown were fastballs. That would be the highest rate of any season in the big leagues since 2017, when it was 56.5%. For reference, here’s fastball usage in college by season.

Although you tend to see analysts say we need to throw less fastballs, this isn’t always the case. There are players who benefit from throwing more fastballs, but those players would be in the minority. The reason for the over generalization of throwing less fastballs is because the majority of the pitchers DO benefit from using their secondaries more often. Every player is unique and for that reason you go about pitch usage based on their strengths/weaknesses. You just tend to see most pitchers benefit from less heaters. It’s also just easier to yell “less fastballs” the same way old coaches yell “just throw strikes” to get the point across.

Now for the why, why do we hate fastballs. For starters, what do hitters see every time they’re in the cage or taking batting practice? Fastballs. Fastballs perform significantly worse than every other pitch type, not only in terms of batted ball results, but also stuff quality, and pitch-by-pitch results.

Fastballs on a PA-level are hurt the most due to their heavy usage in hitter-friendly counts. For this reason, you have to filter out the data based on the situation and compare. First we’ll look at results early in PAs.

At a quick glance, it might look like fastballs aren’t that much worse than other pitches due to the traditional stats (AVG, SLG, etc) but you’re looking at the wrong numbers. Strikeouts aren’t impacting them for one, so that inflates the numbers entirely. Second, the denominator for AVG and SLG is BIP, meaning only pitches resulting in a batted ball, that only represents just 38% of the sample, whereas a pitch-level stat like CSW% is representing every pitch. For that reason, this is where we see the value in non-fastballs: they all get twice as many whiffs, more called strikes and even when the ball is put in play, they perform pretty similarly, although they are put in play less. 42% of fastballs in this sample are put in play, whereas just 34% of sliders, 38% of changeups, and 37% of curveballs are.

Note: if you’re wondering why I would include AVG and SLG despite them being useless in this scenario, it’s because a dozen people would’ve messaged me asking for them had I not.

Now, looking at how these perform in counts that favor the pitcher.

The case for calling a fastball gets even worse when you look at put-away counts. With more PAs ending in this filter, you notice much lower AVG and SLG numbers; fastballs of course have the highest wOBA (which is another way of saying run production) by a wide margin. They also get much less whiffs, and the only real value with fastballs comes when in 3–2 counts due to them having a very slight increase in strike rate. Now, is the difference between roughly 60% strikes and 65% noticable at all in run prevention? Not really. Once you get around or above 60%, the linear relationship between strikes and run prevention becomes stagnant.

Cases of College Pitchers Ditching the Fastball

There’s no better way to hammer home an anti-heater narrative than by showcasing some guys who made a lot of money ditching their worst pitch. Starting with the best pitcher in the country two years ago.

Kevin Kopps’ fastball oddly enough went from a generic four-seam to a solid sinker with some SSW traits due to the supination that made the slider so good, and yet he stopped throwing the pitch all together. Kopps was the Golden Spikes award winner for a reason, and that reason was the slider.

Shawn Rapp didn’t have quite the jump in production like Kopps did, but he dropped his ERA 1.4 runs while throwing pretty much the same number of innings and it was thanks to a 7% increase in sliders (him gaining 7" of sweep on it might’ve helped) and the uptick in changeups was huge too.

Evan Taylor threw more innings this past season than he did in the previous three combined. He’s another guy who turned his generic fastball into a solid sinker and then he started throwing filthy sweepers more. He also ended up getting drafted like Rapp and Kopps.

Bachman isn’t a great example of a guy making huge strides due to pitch usage, but he is a great example of gaining velocity and throwing more breakers as a result. He went from sitting 91–94 as a sophomore to routinely being in the 94–99 range and dropped his heater usage by 21%.

Dombroski might’ve had a slight increase in ERA from 2021 to 2022 but he also only pitched against his conference in 2021 due to the pandemic. Despite the differences in schedules, he posted a career-high in K/9.

Kelley also got drafted recently, and although he had success in previous seasons, he hadn’t ton it over a full one so 2022 was his first season where he put it all together and adding the curve helped clearly.

That’s all I’ve got. It’s really simple, fastballs only add value intrinsically. In order for your secondaries to work, you need hitters to at least think fastball and that’s where the heat comes into play. When you start looking at pitchers individually you’ll be able to game plan their usage but more times than not, less is better with regards to fastball usage.

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