How Dodgers righty Tyler Glasnow added a sinker to his already overpowering arsenal

When Tyler Glasnow was acquired by the Dodgers — and subsequently extended for four years, $115 million — as one of the key transactions of L.A.’s historic offseason, two major questions emerged about the 30-year-old right-hander’s future with his new team: 1) Could Glasnow prove capable of staying healthy over a full regular season, quelling longstanding concerns about his overall durability? and 2) Would Glasnow, already renowned for possessing one of baseball’s most overpowering arsenals, actually improve as a Dodger, and if so, how?

It’s still early, but so far this season, Glasnow has emphatically addressed the first question in encouraging fashion. Saturday’s hiccup in San Francisco aside (he allowed five runs over just three innings against the Giants, marking the first time this season that he failed to complete five innings in a start), Glasnow has averaged more than six innings per start and hasn’t missed a turn through the rotation in the first three months. In many ways, he has carried over the momentum from his final season in Tampa Bay, when he set career highs in both games started (21) and innings pitched (120) despite missing nearly all of April and May. In fact, with 103 completed frames already in 2024, he could set career highs in both categories once again before we reach August.

And as the workload has mounted and impressed, so too has Glasnow’s effectiveness. Seeing his name among the league leaders in innings pitched might feel unfamiliar, but his other National League ranks — 12th in ERA (3.23), first in strikeouts (136), second in WHIP (0.93), first in batting average against (.186) — are hardly surprising considering his supreme talent. Glasnow is in excellent position to earn what will somewhat shockingly be his first career invite to the All-Star Game, an honor that his durability struggles prevented in previous seasons.

That Glasnow has proven his excellence over a larger sample this year isn’t a huge shock, but how he has gone about finding success in Dodger blue is far more notable. And that brings us to our second source of intrigue: After years of Glasnow developing in a Rays organization known for getting the most out of pitchers, what tweaks have the Dodgers made to help him unlock an even higher level of performance?

Most significantly, after years of leaning exclusively on his high-powered four-seamer and two distinct yet similarly dynamic breaking balls (a curveball and a slider), Glasnow has started to incorporate a fourth pitch: a two-seamer, also known as a sinker. In five of his past nine starts, Glasnow has thrown at least 10% sinkers. He threw more than 15% sinkers in his three most recent starts, including nearly 20% on Saturday.

Where did this come from? A pitcher adding a new pitch in the modern age of pitching development isn’t exactly headline-grabbing news, but this recent expansion of Glasnow’s arsenal is fascinating considering his history with the two-seamer. When he was coming up a decade ago as a hard-throwing prospect in the Pirates organization, Pittsburgh placed a heavy emphasis on throwing sinkers either in tandem with or in favor of four-seamers, and Glasnow was no exception. As a rookie in 2017, he threw 34% four-seamers and 33% sinkers. Gerrit Cole, another former top Pirates pitching prospect, also threw a healthy dose of two-seamers early in his career, something he scrapped completely once he left the ‘Burgh.

But while Cole’s sinker was reasonably effective in his early years with Pittsburgh, Glasnow’s was the opposite: Opposing batters hit .431 and slugged .696 against the pitch. By run value, it was one of the worst individual pitches in the league. His changeup, which he threw about 10% of the time, wasn’t much better, yielding a .313 batting average against and an even more troubling .750 SLG%. As a result, Glasnow ditched both offerings when he moved to the bullpen the next season before his trade to Tampa Bay, and neither pitch reemerged in any meaningful way during his six-year stint with the Rays.

With Glasnow’s four-seamer and curveball proving so overwhelming in subsequent years, there did not appear to be a need to alter his approach too drastically upon his joining L.A. in 2024. Yet Glasnow quickly exhibited a willingness to grow his arsenal further and went to work with the club’s pitching brass, led by pitching coach Mark Prior and assistant coach Conor McGuinness, to identify a realistic path forward.

“Every pitch that he throws in his arsenal is turning left,” assistant pitching coach Conor McGuinness told Yahoo Sports, referring to Glasnow’s four-seamer, which naturally has cut to it, and his slider and curveball, which break sharply gloveside as well. For years in Tampa, Glasnow tinkered with a changeup in an effort to find a more traditional off-speed offering and one that would exhibit more armside movement. But through conversations with Glasnow and analyzing how he naturally releases the baseball, McGuinness said, it became clear that a changeup was not a viable option.

“I think it was something where he had always toyed around with the changeup. I believe the changeup was the one that really had previously barked his elbow,” he said. “We never really got into it with him — he’s just got a mental connotation with that pitch that it would receive pain. Knowing him now better, like, I guarantee he was really trying to roll it and make it nastier. And being the natural supinator [that he is], it’s just gonna lead to more harm than good.”

With the changeup off the table, they pivoted to the sinker. “What’s the lowest hanging fruit to improve his arsenal,” McGuinness explained, “without putting him at risk?”

McGuinness and Co. helped Glasnow identify a more subtle two-seam grip that allowed him to throw it like a four-seam, with the grip creating the desired movement, rather than needing to markedly change how he was releasing the ball. In turn, Glasnow is able to throw the pitch at roughly the same elite velocity as his four-seamer — but it darts sharply in the opposite direction.

The key, McGuinness said, is “making sure and teaching him how to actually properly throw it. Some guys will get a two-seam grip and want to manipulate it to create shape. But [the key is] showing him how to hold it and trusting his regular throw.

“I think at times he still tries to shape it a little more than he needs to, rather than just trusting the grip and his natural throw to let it do its thing. But it’s been very good.”

Conversations about pitch shapes and their movement profiles were routine for Glasnow in Tampa Bay, and he has continued to embrace them with the Dodgers.

“He and I can sit down and nerd out about stuff,” McGuinness said. “I can tickle his nerdy brain a little in that realm and whatnot. I think it’s more for him not to feel boxed in on just the three [pitches]. He’s very open to a lot of this stuff. We just want to make sure he maintains doing what he’s doing.”

Although it didn’t start to show up regularly in games until mid-May, Glasnow’s two-seamer had been in the works behind the scenes since spring training. “He had used it on the backfields,” McGuinness said. “He punched out Mookie on one. Mookie and Freddie were not happy with us.”

These days, Glasnow’s MVP teammates need to deal with his new pitch only in scrimmage settings. But the rest of the league isn’t so lucky. And the impact of the two-seamer has been notable.

“You can keep it in the back of other teams’ heads. Now teams can’t sell out to one fastball profile in any given count,” McGuinness said. “You just don’t know which one you’re gonna get. Same velocity, but one’s cutting minus-3 [inches], the other one is running at positive-9 [inches]. So you’ve got to cover a foot.”

While much of the Dodgers’ roster and coaching staff are still getting to know Glasnow, one of his teammates has witnessed his evolution up close for much longer. Left-hander Ryan Yarbrough was one of just a few familiar faces in the Dodgers clubhouse when Glasnow arrived in Arizona this year. The two were teammates in Tampa for five seasons, with Yarbrough making his MLB debut with the Rays just a few months before the team acquired Glasnow from Pittsburgh as part of the deal for Chris Archer at the 2018 trade deadline.

“I played against [Glasnow] in 2017 in Triple-A,” Yarbrough recalled to Yahoo Sports. “It was one of those things where you’d see him, and you’re like, ‘Why is this guy down here?’”

Glasnow — with shoddy command and that sinker that was getting absolutely pummeled — had struggled mightily in the first two months of his rookie season, to the tune of a 7.45 ERA that necessitated a mid-June demotion to Triple-A. Still, Yarbrough’s recollection was wholly appropriate, considering what Glasnow did to Triple-A hitters once he got sent down.

“It was weird because he was down for maybe two-thirds of the season, and he was, like, third in strikeouts,” said Yarbrough, who led the International League in strikeouts that season with 159 in 157 1/3 innings. Indeed, Glasnow was two spots behind him on the leaderboard with 140 — in 93 1/3 innings. “He missed the first two months and came down and was just punching out the world. And we’re like, ‘All right, dude, why are you here?’

“And then [the Rays] trade for him,” Yarbrough said, “and we’re like, ‘We got that guy? Really?!”

Five years later, Yarbrough once again experienced his team acquiring Glasnow and the excitement that came with it — this time with far more certainty about the success that was to come. “Once he got here,” Yarbrough said, “I was like, ‘All right, this guy’s gonna be unbelievable.’”

Armed with a new-and-improved weapon for hitters to worry about, Glasnow has indeed become that much more daunting for opponents. Of the 106 sinkers he has thrown this season, just two have resulted in hits.

Suddenly, the pitch that was once his biggest detriment is one of Glasnow’s greatest strengths.