Blue Jays Prospect Kai Peterson Evolves with Innovative Pitching Style

Toronto Blue Jays pitching prospect Kai Peterson has showcased significant improvements in his performance as he adapts his technique following Tommy John surgery. Initially reaching a maximum of 87 mph during his bullpen sessions, Peterson found inspiration in a video of fellow left-handed pitcher Josh Hader. Emulating Hader’s unique windup and arm angle, Peterson increased his velocity to 91 mph, marking a pivotal moment in his development.

“The more I dove into the low-release-height stuff, that’s something I think will honestly end up being the future of baseball,” Peterson stated. He highlighted the success of pitchers like Trey Yesavage, who uses an exceptionally high release point, causing difficulties for hitters. Peterson, who spent part of the 2024 season with double-A New Hampshire and recently concluded his time in the Arizona Fall League, believes that experimenting with release heights is crucial in a league where many pitchers throw at high velocities.

Transitioning from a traditional over-the-top delivery to one that releases roughly at shoulder height has been instrumental in Peterson’s journey. After fully recovering from his surgery, he secured a spot at Sacramento City College for the 2021-22 season. The following year, he moved to Sierra College, where the Blue Jays selected him as their 20th-round pick in the 2023 MLB Draft.

In 2024, Peterson struck out 91 batters in 49.2 innings across low-A Dunedin and high-A Vancouver. He followed that with an impressive 61 strikeouts in 50.1 innings this season, while improving his walks-per-nine rate from 7.8 to 5.2. His main areas of focus now include increasing his command and refining his slider, as he continues to draw attention from the Blue Jays, who are keen on diversifying their pitching options.

The Blue Jays have shown a growing interest in pitchers with unique delivery styles. For instance, the club’s acquisition of Adam Cimber in 2021 and the emergence of rookie lefty Mason Fluharty this season reflect this trend. Peterson’s collaboration with pitching coach Eric Yardley in Vancouver has also contributed to his development. Yardley, who experienced a successful career in the majors, transitioned to a sidearm delivery during his collegiate years, which enhanced his effectiveness on the mound.

“Velocity is still king,” Yardley noted. He emphasized the importance of varying release angles, especially for pitchers who may not possess elite velocity. “If you can’t find velocity, or if you are still in that average to slightly-above-average category and you need to make a change… some of those arm slots and abilities to move the ball differently are finding value again,” he added.

Yardley’s insights from his time with Milwaukee in 2020 and 2021 illustrate the effectiveness of a diverse pitching staff. He highlighted how different release points helped the team strategize effectively based on the strengths of their pitchers. “At one point, we had David Phelps, you keep going, and you get Devon Williams… so that when you want to have a specific form of success, you can bring in the groundball pitcher, or the strikeout pitcher.”

Peterson is acutely aware of what has driven his success thus far. He reflects on the evolution of his arm angle, which he has gradually become more comfortable with. “The slot that I’m at now was something that built over time,” he explained. “There are still mechanical things I want to work on this off-season, too, to get back to throwing harder again.” He noted that during the middle of the season, he reached speeds of 94 to 96 mph before facing challenges related to fatigue and natural physical changes throughout the season.

To address these challenges, Peterson aims to regain approximately 10 pounds he lost during the season. He is also experimenting with different grips for his slider. Conversations with pitching development coordinator Ricky Meinhold have centered on optimizing the pitch’s movement profile to better complement his fastball, which currently runs 18 inches arm-side.

Peterson has tapped into his past experiences, particularly the challenges he faced following his elbow injury during his senior year of high school. While the injury initially felt like a setback, it ultimately proved to be “kind of a blessing in disguise.”

“Looking back at it, I was probably going to need it no matter what. I just got really lucky,” he said. “It sucked at first, but then I just used that as a time to grow… I built a stronger work ethic, paying attention to little details. So it really was probably the best thing that happened in my career.”

As Peterson continues to refine his skills, he represents a new wave of pitchers who are finding success through innovation and adaptability in their craft. With his evolving style and the support of the Blue Jays organization, the future looks promising for this talented prospect.