Article: Chris Bassitt's New-Ish Toy

[Leo Morgenstern]

On Friday, Chris Bassitt took the mound against the Athletics, his team from 2015 to 2021. His final year with the A’s was arguably the best he's ever had. He went 12-4 with a 3.15 ERA. He was an All-Star for the first (and so far only) time. His 4.0 Baseball Reference WAR ranked eighth among AL pitchers. His 3.3 FanGraphs WAR ranked 11th. Both were career-highs.

Four years and two teams later, the veteran right-hander is a very different pitcher. His primary fastball is still a sinker, but his velocity is down by a mile and a half. Even accounting for the change in velocity, the pitch drops more than it used to. And that's just the tip of the iceberg. Bassitt's average arm angle is six degrees lower than it was in 2021, while his average release point is more than a foot closer to third base. He throws his curveball far more and his four-seam fastball much less. He no longer throws his changeup at all. Instead, his splitter has become his primary off-speed pitch – and that’s what I’d like to talk about today.

Bassitt introduced a splitter to his arsenal when he joined the Blue Jays in 2023. If you've been paying close attention to the types of pitches this team likes to throw, that shouldn't come as a huge surprise. Over the past four seasons, the Jays have thrown significantly more splitters than any other club (per Statcast). Just under 7% of all pitches the Jays have thrown since 2022 have been splitters. The league median is 2.2%, while no other team is above 5% in that time. This is largely because of Kevin Gausman, who throws both a ton of innings and a ton of splitters. However, the Jays have acquired and developed several more splitter-throwers than just Gausman over the past few years (including Erik Swanson, Bowden Francis, Yariel Rodríguez) and encouraged many of them to use their splitters more regularly. 

Bassitt threw his splitter sparingly at first, and almost exclusively to opposite-handed hitters. He used his splitter 6.5% of the time against lefty batters in 2023 and 7.2% of the time in 2024. This year, that rate is up to 13.1%. Meanwhile, he only threw one lone splitter (that very well could have been miscategorized) to a righty batter in 2023 and only 15 (1.1%) in 2024. Twelve starts into 2025, he's already tossed 16 splitters to righty batters. That’s a low number, but it represents close to a threefold increase in splitter usage against righties compared to last season. All told, Bassitt has thrown his splitter 8.6% of the time this year, making it his fourth most common offering; last year, it was number eight.

Here's what's strange about Bassitt throwing his splitter so much more this year: It's not a very good pitch. The table below shows how it has performed over the past three seasons. It's hard to look at these results and think, "That's a pitch he should be using more!"

Season	wOBA	xwOBA	Whiff%	PutAway%	Run Value
2023	.377	.353	22.6%	9.1%	-2
2024	.313	.365	16.7%	11.5%	-3
2025	.533	.437	21.1%	7.4%	-5

It also grades out poorly according to all of the pitch modeling statistics at FanGraphs (Stuff+, Location+, & Pitching+ and PitchingBot Stuff, Command, and Overall) and Baseball Prospectus (PitchPro and StuffPro). To be fair, Bassitt's splitter is clearly still a work in progress. The pitch's velocity, spin rate, and movement profile have changed noticeably in each year he has thrown it. Yet, if anything, that only makes it more surprising to see him throwing his splitter twice as often in 2025. What made him decide it was ready for a more prominent role in his arsenal?

Perhaps we can answer that question by looking at how he uses the pitch. Bassitt throws his splitter outside of the strike zone more than two-thirds of the time. That's unusually high, even for a pitch type that tends to be thrown as chase bait – and especially coming from a guy who tends to throw more strikes than the average pitcher. Over the last three years, Bassitt has thrown 52.5% of non-splitters in the strike zone, compared to a 49.9% league average. However, he has only thrown 30% of his splitters in the zone, compared to a 37.2% league average. Take a look at this chart from Baseball Savant that shows the in-zone rate for all of Bassitt's pitches. His splitter is the teal-colored line way below all the others:

As you can tell from the full rainbow of colors in the graph, Bassitt is the type of pitcher who succeeds by keeping his opponents guessing with all sorts of different looks. One reason he uses his splitter is simply that it's different from his other pitches. Bassitt needs "different" to survive, even if "different" doesn't always mean "better" (or even "good"). 

To that point, Bassitt has dropped his changeup from his arsenal after giving up a career-worst 11.5% barrel rate, .440 wOBA, and .364 xwOBA on the pitch last year. His splitter is a different beast, but he throws it at about the same velocity and with a relatively similar movement profile. So, his increased splitter usage might not really be about the splitter at all. Rather, he might just need an offspeed pitch that tunnels well with his sinker, and he no longer trusts his changeup to fill that role. Like I said, Bassitt's modus operandi is keeping opponents on their toes by throwing different pitches in different locations at different speeds and with different movement profiles. His splitter is far from perfect, but ultimately, the fact that it's different might be good enough.

Additionally, it's worth noting how many of his out-of-zone splitters have been in the area Statcast calls the shadow zone, which goes from roughly one baseball's width inside the zone to one baseball's width outside the zone. A lot of Bassitt's in-zone splitters have been in the shadow zone as well. All told, he's thrown 50% of his splitters in the shadow zone this year, the highest rate of any of his pitches. As I theorized a couple of weeks ago, living in the shadows seems to be helping Bassitt expand the strike zone as a means of inducing more chase. (That's something he can afford to do because of how well the Blue Jays' catchers frame pitches.) So, while his splitter might not look effective in and of itself, it could be part of a larger plan that is paying off. No matter what the numbers say about his splitter, you can't argue that Bassitt hasn't been successful this season.

Indeed, Bassitt has not walked a batter on a splitter this year, even though he throws it outside of the strike zone so often. And despite throwing more splitters in 2025, his walk rate has never been lower. I think it's safe to presume that all these splitters outside the zone aren't just a matter of poor control. Bassitt locates his splitter where he does for a reason. Is it a good enough reason, considering how poorly the pitch has performed? I can't say for sure. Yet, given how well Bassitt has pitched this season, I'd say he's earned the benefit of the doubt. 

All stats in article updated prior to games on Sunday, June 1.

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[Spanky__99]

Thanks Leo, I enjoy your write ups both on here and Fangraphs for what it's worth. Cheers dude.

[Leo Morgenstern]

10 hours ago, Spanky__99 said:

Thanks Leo, I enjoy your write ups both on here and Fangraphs for what it's worth. Cheers dude.

Thanks a lot, I really appreciate hearing that!

[Mike LeSage]

Love this breakdown. Bassitt's arsenal is so varied and changing that this kind of analysis really helps bring an understanding to the methods behind his 'madness'.