A’s claim White Sox left-hander Joe Rock off waivers, sending him to Las Vegas

The Athletics announced they have claimed left-hander Joe Rock off waivers from the Chicago White Sox. The transaction, completed on the 2026-08-16 afternoon, brings a former White Sox pitching option to Oakland as the A’s continue building out their major-league bullpen and pitching depth.

Rock’s path to Oakland started when the White Sox moved him off their active roster by designating him for assignment two days earlier. After clearing the DFA window, he became available on waivers, allowing Oakland to take over his contract and organizational rights at the major-league level.

Once the A’s claimed Rock, they optioned him to Triple-A Las Vegas, their top farm affiliate in the minors. That move indicates the A’s view him as immediate organizational pitching depth rather than a guaranteed spot in the daily rotation or bullpen workload at the major-league level right away.

Roster mechanics mattered in this claim. To clear a 40-man roster spot for Rock, Oakland transferred right-hander Justin Sterner to the 60-day injured list. The 60-day move is commonly used when a club needs additional space on its 40-man roster while keeping a player unavailable at the major-league level for the longer IL window.

For Oakland, that sequencing suggests the claim was part of a broader roster management plan, not simply a one-off waiver pickup. In August, clubs that are reshaping their pitching staffs often weigh how quickly a newly acquired arm can help at the big-league level against how much roster space they must open to keep other options viable.

For Chicago, the decision to remove Rock from the 40-man roster and expose him on waivers reflects a judgment about where he fit within the organization’s near-term plans. A claimed waiver player can sometimes return to relevance if the new team’s development approach aligns with his pitching profile and usage, but the outcome depends on how he performs once he begins working regularly in the new organization’s minor-league environment.

What to watch next is how Oakland uses Rock in Triple-A Las Vegas, particularly the schedule and role the A’s choose for him. If his assignments point toward a longer bullpen stint or targeted innings as he builds back to peak command, it could foreshadow a later recall. Conversely, if he needs extended time to refine pitches or stamina, the earliest major-league impact may be further down the road.

The other key storyline will be Sterner’s 60-day injured list designation and how Oakland’s pitching depth looks once the organization begins reacting to injuries and workload in the coming weeks. Because the A’s used the 60-day IL to make room for Rock, their next roster moves may reveal whether Sterner’s absence is expected to be long or whether it creates a temporary opening they can later address through future transactions or promotions.