Jack Flaherty's Two First Halves: How He Started Looking Like the Starter Detroit Expected
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Just six starts ago, Jack Flaherty looked headed for a forgettable first half. He carried a 5.81 ERA through his first 12 outings, the Tigers had lost 10 of those games, and the right-hander was still searching for answers.
Two months later, the conversation has changed.
Flaherty heads into the All-Star break with a 2.12 ERA over his last six starts, three wins, and the look of the pitcher who convinced the Detroit Tigers to invest in him. The most interesting part of that turnaround, however, is that it did not come from adding a new pitch or overhauling his repertoire. It came from executing the same arsenal much more consistently.
The numbers highlight the contrast.
Category | First 12 GS | Last 6 GS |
|---|---|---|
ERA | 5.81 | 2.12 |
FIP | 4.64 | 2.47 |
HR/9 | 1.4 | 0.3 |
BB/9 | 5.1 | 3.0 |
K/BB | 2.1 | 3.4 |
The drop in ERA stands out, but FIP tells an equally important story. By focusing only on the outcomes a pitcher controls—strikeouts, walks, and home runs—the decline from 4.64 to 2.47 suggests the improvement is not simply the result of better luck.
Perhaps the most surprising part is that Flaherty's strikeout rate barely changed. He averaged 10.9 strikeouts per nine innings over his first 12 starts and 10.3 over his next six. He also did not suddenly begin pitching much deeper into games, increasing only from 4.4 to 4.9 innings per start.
The real story lies elsewhere
During the first two months of the season, Flaherty struggled to throw efficient strikes. Opponents consistently worked quality at-bats, taking advantage of his inconsistent command and hittable pitches in the strike zone. He issued 30 walks and allowed eight home runs over his first 52⅔ innings. Across his next 29⅔ innings, he gave up only 10 walks and a single homer.
Eliminating those two outcomes changed the profile of his starts. He did not need to miss significantly more bats to become a much more effective pitcher. That shift also becomes clear when examining his primary pitches.
His four-seam fastball provides the best example.
During his first 12 starts, opponents hit .266 with a .440 slugging percentage against the pitch. Over his last six starts, those numbers dropped to .140 and .200, respectively. At the same time, the fastball's strikeout rate jumped from 11.5% to 26.3%, while both hard-hit rate and barrel frequency declined.
Hitters vs. Four-Seam Fastball — First 12 Starts
Hitters vs. Four-Seam Fastball — Last 6 Starts
The difference is not that Flaherty stopped throwing his fastball. He simply began winning far more battles with it by consistently producing higher-quality pitches.
Much of Flaherty's turnaround can be traced to where he located that four-seam fastball, and the Statcast heat maps leave little room for debate.
During his first 12 starts, hitters feasted on pitches left in key areas of the strike zone. They batted .400 against fastballs in the lower-middle portion of the zone (Zone 8), .667 in the lower-away corner (Zone 9), and .364 in the upper-away portion (Zone 3). Those areas became some of the most productive parts of the zone for opposing hitters.
Over his last six starts, the picture looks completely different. Batters hit just .125 in Zone 8, .333 in Zone 9, and failed to record a hit in Zone 3. The biggest improvements came at the top of the strike zone, where Zone 2 dropped from a .333 average allowed to .000, while Zone 1 fell from .200 to .000.
Rather than leaving fastballs over the heart of the plate, Flaherty has consistently worked the edges of the strike zone, turning previous weaknesses into strengths. It is no coincidence that his fastball strikeout rate climbed from 11.5% to 26.3%. Better location has forced hitters into more chases and more empty swings.
The fastball accounted for much of the turnaround, but it was not the only adjustment. His slider generated more swings and misses while virtually eliminating walks, and his knuckle curve produced stronger expected metrics than its surface results suggested.
That mix was on display Thursday night at Comerica Park, when Flaherty delivered six solid innings in Detroit's 10-2 victory over the Philadelphia Phillies. He allowed two runs, struck out six, and generated 14 swinging strikes. Half of his strikeouts came with the knuckle curve.
After his final start before the All-Star break, Flaherty's season now feels split into two distinct halves. The first raised legitimate concerns. The second reminded everyone why Detroit believed he could anchor its rotation.
The question now is which version the Tigers will get over the rest of the season?
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Yirsandy is a baseball writer specializing in MLB coverage with experience across multiple teams and storylines. He currently writes for Diamond Centric, where he covers the New York Mets, San Diego Padres, Chicago Cubs, Milwaukee Brewers, and Kansas City Royals. My work focuses on game coverage, player analysis, and storytelling that connects performance with context. My Substack has also been an important part of my writing development, where I’ve built much of my baseball coverage and storytelling voice over time. I’m passionate about combining reporting, research, and thoughtful analysis to produce engaging baseball content for readers.
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