In the world of sports, especially in baseball, the phrase "the grass isn’t always greener" rings particularly true. Often, the skies aren't necessarily bluer either, as George Kirby is discovering in his professional journey.
Kirby has flourished in Seattle, a city that aligns perfectly with the Mariners’ organizational philosophy, which emphasizes minimizing walks and maintaining control over counts and zones. This intensity is evident both on the mound and in his overall approach to the game. As a fly ball pitcher who has historically thrived on inducing contact, it’s clear that Kirby has benefitted from being drafted into the Mariners’ system. However, 2025 marked a significant turning point for him.
Nothing catastrophic occurred for Kirby, yet he certainly started the season on a challenging note. He was sidelined due to shoulder inflammation, coupled with persistent knee issues that led to an extended absence from pitching. This marked his first-ever stint on the injured list during his major league career. Upon his return, Kirby faced unprecedented struggles. He encountered significant difficulties right out of the gate against teams like the Astros and Nationals, spending much of the season trying to regain his form. Despite racking up an impressive tally of 37 strikeouts against the Angels, while allowing only three walks and six earned runs over 19.1 innings, his performance against the rest of the league left much to be desired, culminating in a 4.64 ERA and a 3.58 FIP across 106.2 innings pitched.
When reviewing Kirby’s last season, two prominent narratives emerge. The first is his newfound willingness to pitch outside the strike zone, resulting in his highest walk rate to date. At 5.5%, this figure still ranks as the 18th lowest among pitchers who logged at least 120 innings (of which there were 105). However, it’s worth noting that he had previously ranked 6th, 1st, and 2nd in this category since his entry into the league. Is this cause for concern? Not necessarily. Kirby's strikeout rate also saw an uptick, possibly as a strategic adjustment or simply a response to the challenges he faced (more on that shortly). His K-BB% rankings over the past few seasons have been consistently strong, reflecting his ability to maintain high-quality performance even as he made alterations to his pitching style and approach.
Yes, Kirby did venture outside the zone more than ever before, and the outcomes were largely what one would expect. He recorded more swings and misses than in previous years, achieving the best called strike-plus-whiff percentage of his career. Although he observed fewer swings overall and saw a dip in chase rates, the swings he did induce were often less effective. If Kirby aimed to reduce the vulnerability associated with his previous tendency to pound the strike zone, he only achieved partial success. While hitters were whiffing more frequently, they also managed to make solid contact more often—a puzzling aspect of assessing Kirby’s season. It raises questions about the relationship between his injuries, any lingering rust, and potential conscious adjustments he made along the way.
During his recovery, Kirby opted to cut back on his splitter and barely utilized a less effective changeup due to comfort issues with the pitch. Was this change in his arm slot, which altered the movement characteristics of his sinker, slider, and curveball, a tactical decision? Or was it merely a compensatory measure due to the discomfort he experienced earlier in the season? What was his strategic plan, and what adjustments were made in response to the challenges he faced?
The second notable aspect of Kirby’s performance last season is exemplified by his overall statistics, featuring a 4.21 ERA alongside a 3.37 FIP. We’ve come to understand that batted-ball outcomes can’t solely be attributed to luck anymore. As previously mentioned, Kirby wasn’t giving up purely hard-hit balls; a modest increase in hard-hit rate doesn’t sufficiently explain why he had the ninth highest ERA relative to FIP among the same group of pitchers. Interestingly, three of the top ten in this category were expectedly Colorado Rockies pitchers, with the Diamondbacks and Phillies also making appearances.
Experiencing a season as challenging as this typically involves a degree of misfortune, a sentiment shared by players like Dylan Cease and Sonny Gray. Yet, performing poorly in Seattle, where the pitching environment generally favors hurlers, raises eyebrows. Kirby’s 0.85 discrepancy between his earned run average and FIP marks the worst gap for a Seattle starter over the past decade at this workload level. The last time a Mariners pitcher had such a tough stretch was Marco Gonzales in 2018, whose 0.57 gap was the 15th largest in MLB. To find someone who endured more adversity than Kirby in T-Mobile Park history, you’d have to look back to James Paxton in 2016, who also faced significant struggles despite later achieving several remarkable seasons.
At this point, we encounter a wall of complexity when evaluating Kirby's situation. While some of his challenges are interconnected with defensive shortcomings, neither his BABIP nor contact outcomes suggest that his performance was egregiously poor. Instead, it appears that Kirby's mistakes were disproportionately punished, even when those mistakes didn't leave the park, preventing him from executing the efficient, methodical pitching style that characterized his previous seasons.
Looking ahead to 2026, Kirby seems poised to prove that he is not satisfied with how the past year unfolded. His splitter, initially developed as a nod to Kevin Gausman’s signature pitch, was cast aside due to comfort issues, leaving him somewhat constrained in his capabilities. If he intends to reintegrate this pitch into his repertoire for the upcoming season, as has been hinted, it could significantly aid his efforts to refine a strikeout-oriented approach. Just a year ago, many believed Kirby was on the verge of establishing himself as an ace within Seattle's rotation. Now, after facing the most challenging season of his young career, he may finally possess the motivation he needs to fuel his drive: a chip on his shoulder.
