Former KC Royals flamethrower returns to Kansas City baseball

After a brutal 10‑game swing against the AL’s elite, the Kansas City Royals finally caught a breather at home on Monday. Fans scanning the rumor mill for blockbuster trades or bullpen shake‑ups were left wanting as the clubhouse stayed quiet. But as the workweek kicked off, one familiar arm found a new gig back in Kansas City.

The Kansas City Monarchs announced they signed left-handed pitcher Jake Brentz for the 2025 season. The southpaw is one of the Monarchs' final roster additions, as they are now at 29 players with a 30-man roster limit for spring camp, and that needs to be whittled down to 25 players ahead of May 9, their Opening Day.

“Jake Brentz is a high-velocity guy with major-league experience,” Monarchs manager Joe Calfapietra said. “We think he has a ton of upside and are excited to see him get going with us.”

It wasn't long ago that the KC Royals invested in reliever Jake Brentz.

Brentz’s Kansas City journey started as a low‑risk flier: the Royals signed the hard‑throwing lefty to a minor‑league deal in 2019, saw his stuff, and slotted him onto the Opening Day roster in 2021. He repaid that faith with triple‑digit heat (95–100 mph) and a wipe‑out slider that held hitters to a .191 average, quickly earning him high‑leverage opportunities. After debuting on April 3, 2021, Brentz notched his first big‑league save by early August at the South Side of Chicago, capping a rookie season with 72 appearances (tied for the team lead), a 3.66 ERA, 10.7 K/9 and a stingy .197 opponent batting average.

His momentum stalled in 2022. Brentz began the season as a trusted late‑inning option, but erratic command (10 walks over 5 1/3 innings) and a flatter fastball caused his ERA to skyrocket to 23.63 in just eight outings. An MRI confirmed a torn UCL, and he went under the knife for Tommy John surgery in July—knocking him out for the rest of 2022 and all of 2023. Kansas City non‑tendered him that November, then immediately re-signed him on a two‑year, $1.9 million deal, betting that the 2021 version of Brentz would return once his elbow healed.

Brentz’s comeback hit a snag almost immediately. A stubborn lat strain in 2023 limited him to just 2 1/3 rehab innings, and his command wobbles carried right into 2024’s Cactus League. When the Royals needed 40‑man roster space last June, they outrighted him and he opted for free agency. Tampa Bay rolled the dice on Brentz this winter, but after an up‑and‑down spring, the Rays cut him loose on March 13, 2025—clearing the runway for his next landing spot.

In 69 1/3 innings with Kansas City, Brentz posted a 5.19 ERA with 85 strikeouts, 47 walks and two saves. Though his overall stat line looks patchy, Royals fans won’t forget that 2021 breakout—a homegrown fireballer who, for one thrilling summer, seemed destined to anchor the late innings. If his new club can reignite that peak form, they’ll be unleashing the same high‑octane arm Kansas City once envisioned closing out games at Kauffman Stadium.

The Monarchs compete in the 12‑team American Association of Professional Baseball—one of MLB’s Partner Leagues that crisscrosses the Midwest. Each summer, clubs grind through a 100‑game slate before only four survivors clash in a win‑or‑go‑home playoff. Kansas City’s franchise has already hoisted the Miles Wolff Cup three times, most recently in 2023.