Former top-five Royals prospect gets the MLB call with struggling Athletics

Every day of the baseball calendar brings a flood of transactions. It’s easy enough to track the Royals on social, but keeping tabs on the other 29 clubs—especially with how active teams have been lately—is tougher.

Case in point: the Athletics promoted right-hander and former Royals prospect Mason Barnett to The Show, a move that may have slipped through the cracks. It’s also the first meaningful data point in judging whether Kansas City ultimately “won” last season’s Lucas Erceg trade.

Former standout Royals prospect Mason Barnett got the awaited MLB call.

Barnett spent the entire 2025 season with Triple-A Las Vegas, and his results there have been far from impressive. Across 23 starts and two long-relief outings, he’s logged 119 innings with a 6.13 ERA.

Some of that can be pinned on the hitter-friendly Pacific Coast League, as his 15.6% home run-to-fly ball rate is easily the highest of his career. His 22.8% strikeout rate sits around league average, but the 11.9% walk rate tilts heavily in the wrong direction.

Despite the shaky stat line, Baseball America still ranks Barnett as the ninth-best prospect in the Athletics’ system, while MLB Pipeline has him just outside the top 10 at 11th.

Both outlets see mid-rotation potential, citing his pitch mix: a mid-90s four-seamer complemented by a sweeper, curveball, and changeup. Barnett was set to be Rule 5 Draft–eligible this winter and would have required a 40-man roster spot for protection, so the A’s may simply be making that move a little early—especially with left-hander Jacob Lopez landing on the 15-day IL.

When Kansas City acquired Erceg, the price tag raised eyebrows. The Royals sent Barnett, reliever Will Klein, and outfielder Jared Dickey to Oakland. At the time, some balked at paying that much for a setup man, but Erceg quickly justified the cost, anchoring the bullpen down the stretch in 2024 and remaining a key piece in 2025.

While Klein had already debuted in the majors, Barnett was unquestionably the headliner of the deal from the Athletics’ perspective.

The Royals drafted the Auburn right-hander in the third round of the 2022 MLB Draft, and Barnett quickly climbed their prospect ranks. Kansas City ultimately dealt him when his perceived value was at its peak, and his struggles since leaving the organization have only reinforced the perception that the Royals came out ahead in the Erceg trade.

It remains to be seen whether Barnett will stick as a starter or shift into a bulk-relief role for the Athletics, but first impressions matter at the MLB level. With Oakland out of contention in 2025, an early big-league look could be exactly what the Georgia native needs to steady his professional trajectory.