Jack Flaherty is an emotional pitcher.

He pitches angry.

He's been that way since high school, when Harvard-Westlake baseball coach Ethan Katz, now the pitching coach of the Chicago White Sox, would pull Flaherty aside in hopes of getting him to calm down. The lessons of controlling his emotions continued into his professional career, mentored by St. Louis Cardinals legend Adam Wainwright.

"It's like a line that I walk when I pitch," Flaherty said. "If I go too far, then we're out of control, but if I can be right on that line of feeling like I have just enough of an edge but be in control, that's where I want to be. It's not an easy thing to do."

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Even at age 28, Flaherty — an established right-hander who has revived his career with the Detroit Tigers this season — talks with Tigers pitching coach Chris Fetter about needing to stay in control of his emotions. To stay in control, Flaherty makes emotional adjustments throughout every start.

"It's not something that is always perfect every day," Flaherty continued. "Some days, I got to pull it back. Some days, it's not there, and I got to find a way to bring it out."

Flaherty, who signed a one-year, $14 million contract last offseason, is one of the most coveted players in trade discussions as Tuesday's trade deadline approaches because of his elite performance while pitching on an expiring contract.

The Tigers plan to trade him.

In 2024, Flaherty has a 2.95 ERA with 19 walks and 133 strikeouts across 106⅔ innings in 18 starts. His career-best 32% strikeout rate ranks fifth among 75 pitchers with at least 100 innings; his career-best 4.6% walk rate ranks eighth.

"He's been a rock for us," said Tigers outfielder Mark Canha, a 10-year MLB veteran. "He's one of those guys where you're like, 'Man, where would we be without him?' What he's been doing all year is awesome."

It's arguably Flaherty's best season of his eight-year MLB career, mirroring his dominance in 2019 and 2021.

"When you see him going through those stretches that he can have where he is absolutely dominant, he controls his emotions really well," said Wainwright, Flaherty's longtime teammate, mentor and friend. "The times that you see him struggle a little bit is when he lets the ferocity that he performs with go a little bit too far, but he has gotten so much better at controlling his emotions."

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The Cardinals drafted Flaherty with the No. 34 overall pick in 2014 out of high school. Three years later, Flaherty impressed veteran pitchers like Wainwright in his first big-league camp in spring training, then made his MLB debut in September 2017.

That spring, a 21-year-old Flaherty showed athleticism, work ethic and extreme intensity. But Flaherty had to figure out how to cool down at times, if he wanted to execute his pitches.

Flaherty took advice from Wainwright.

"He was good at listening," Wainwright said. "He would let me speak into his life. I felt like he was kind of like my little brother, so it wasn't just about pitching. He wears his emotions on his sleeve. I always felt like one of my roles in that clubhouse was to help young players along, but Jack and I had a special relationship in that way."

In 2024 with the Tigers, Flaherty is pitching like he did in 2019 and 2021 with the Cardinals. He posted a 2.75 ERA across 33 starts in 2019, finishing fourth in voting for the National League Cy Young Award. He also registered a 3.22 ERA in 17 games in 2021, though oblique and shoulder injuries cut his season short.

Flaherty had a 0.93 ERA in his final 106⅓ innings of 2019.

"Once he gets that ball rolling downhill, it is very, very hard to stop him," Wainwright said. "He has such deep belief in himself that when he gets those things rolling, it's really impressive. I know he was hurt when he got hurt in '21, but we were all devastated for him, too. He probably would have won the Cy Young."

In both years, Flaherty controlled his emotions.

He is doing the same in 2024.

"He pitches with a fire that is bordering on anger at all times to get the most out of his ability," Wainwright said. "He is bordering on turning into a ball of fire. He could turn into lava at any moment out there, but he doesn't. He teeter totters a lot with that edge."

The way Flaherty pitches — emotional but under control — reminds Wainwright of fellow Cardinals great Chris Carpenter.

"I see a lot of Carp in Jack," Wainwright said.

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To get back on track, Flaherty made multiple adjustments leading up to the 2024 season. The tweaks, suggested by the Tigers, helped him repeat the mechanics of his delivery and be consistent with the best versions of his fastball and slider.

To do that, Flaherty changed the way his body moved down the mound by activating his gluteal and hamstring muscles, rather than using his quadricep muscles. For his slider, Flaherty eliminated the cutter — a pitch that profiles somewhere between a slider and a fastball — from his pitch mix.

"It was adjustments to repeat those things," said Flaherty, who had a 4.99 ERA in 29 games with the Cardinals and Baltimore Orioles in 2023. "I didn't do those things very well last year, and I was hurt in '22, but the stuff that works is always going to work."

Tigers left-hander Tarik Skubal, the frontrunner to win the American League Cy Young Award, has been impressed by Flaherty's ability to execute and manipulate his slider, describing his slider execution as "the best I've ever seen." He owns the best swing-and-miss rate among qualified pitchers this season, largely because of his slider.

Skubal tried — and failed — to learn Flaherty's slider.

"I've tried to figure out his slider probably every day all season to add to my repertoire, but I haven't been able to do it," Skubal said. "Maybe that's a second-half thing. I watched it one time and was like, 'I want it.' I throw the same grip, but my ball doesn't do the same thing as his does."

The adjustments unlocked the best version of Flaherty, but after making the adjustments, Flaherty had to find steady dominance again. He recaptured his edge by controlling his emotions on a start-to-start basis, just like in St. Louis.

Flaherty has talked with Fetter about these things.

"I play being too far on purpose and reign it back," Flaherty said. "If I'm like, I talked to Fett about this, not like too cool for school, but that's how it looks when I'm super, super relaxed, and the stuff is different. It doesn't have the same bite. It's not as aggressive. It's nibble here and nibble there, instead of a 'F-U, here it is, here's my shit.' I'm able to use that energy to go out and pitch."

Meanwhile, Fetter and manager A.J. Hinch joke that Flaherty is always finding a reason to be angry, but in all seriousness, they know it's a key part of Flaherty's success.

There's a fierce presence about Flaherty when he steps on the mound and stares down his opponent.

"I mean, that's part of his personality," Hinch said, "but he never really strays too far from the competition. ... It's dangerous to pitch with emotion unless you can control it. Some guys need it. When it's handled that way, we're all for it."

Flaherty already has eight MLB seasons, but he hopes his revival in 2024 with the Tigers — even if he isn't going to finish the season as a Tiger — greenlights a career that resembles the two pitchers who paved the way for him.

He's on the right track.

"I hope to do it as long as those guys did," Flaherty said, referencing Wainwright's 18-year career and Carpenter's 15-year career. "I'll let the wheels fall off. That's all I know."

Contact Evan Petzold at epetzold@freepress.com or follow him @EvanPetzold.

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This article originally appeared on Detroit Free Press: Detroit Tigers' Jack Flaherty all about control: pitching and emotions