Athletics call up Gage Jump for MLB debut against Mariners
Aaron Civale’s shoulder sent the A’s to Gage Jump, a 23-year-old lefty with a No. 3 system ranking and a 99 mph fastball, for his MLB debut in West Sacramento.
The Athletics turned to one of their fastest-rising arms, promoting Gage Jump from Triple-A Las Vegas to start against the Seattle Mariners and make his major-league debut after Aaron Civale landed on the 15-day injured list with right shoulder tendonitis.
Jump’s arrival carried real urgency. The 23-year-old left-hander entered the day ranked as the A’s No. 3 prospect and No. 41 overall by MLB Pipeline, and his call-up came only days after he was named Pacific Coast League Pitcher of the Week for May 18-24. That honor followed one of the sharpest outings of his season at Triple-A, when he worked seven scoreless innings without a walk and struck out nine for Las Vegas.
The move also reflected how quickly the A’s rotation had thinned. Civale lasted just four innings in Monday night’s 9-2 loss to the Mariners at Sutter Health Park in West Sacramento, allowing seven runs on nine hits and one walk before the club moved him to the IL. Manager Mark Kotsay said after that game that Civale would undergo testing and was “most likely” headed for the injured list. Civale later said he first noticed something was off in his previous start against the Angels in Anaheim.
To open a 40-man roster spot, the Athletics transferred Denzel Clarke to the 60-day injured list. Clarke has a significant left hamstring strain suffered during a rehab assignment in Triple-A Las Vegas and is expected to remain out until at least after the All-Star break.
Jump reached this point quickly after the A’s took him 73rd overall in the 2024 draft out of LSU. He made his pro debut in 2025 and entered this season as one of the organization’s most intriguing young arms. His fastball has reached 99 mph, and he complements it with a slider, changeup, curveball and sweeper, a mix that gives Oakland a look at a starter with both velocity and pitch variety.
The raw numbers from Las Vegas showed both the promise and the growing pains that often come with a fast track. In nine Triple-A starts this season, Jump went 0-2 with a 4.50 ERA, 56 strikeouts and 20 walks in 38 innings. Even with the uneven run prevention, the strikeout total and the week-to-week swing in his stuff clearly pushed him toward Oakland sooner rather than later.
For the A’s, the debut was about more than filling one start. With the rotation unsettled behind Luis Severino and Jeffrey Springs, Jump’s promotion marked a direct bet on upside, and a reminder that the club’s next wave is already being asked to handle the majors now.
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