Mariners Sign 26-Year-Old Catcher, Former Cardinals Draftee

Stocking up on future backup candidates...

Jun 5, 2022; Arlington, Texas, USA; A view of a Seattle Mariners batting helmet and logo during the game between the Texas Rangers and the Seattle Mariners at Globe Life Field. Mandatory Credit: Jerome Miron-Imagn Images | Jerome Miron-Imagn Images

The Seattle Mariners quite obviously have their starting catcher of the future, but that isn't preventing them from keeping the farm system stocked.

In Cal Raleigh, the Mariners have the consensus top catcher in all of baseball, fresh off a 60-homer season. Seattle traded away top prospect Harry Ford this offseason, which made sense because he deserved an opportunity to play more often than having Raleigh would have allowed, but which also left the pipeline of future backups relatively dry.

The Mariners' latest minor-league signing was designed to solve that shortage.

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Mariners sign Aaron McKeithan

Feb 18, 2025; Bradenton, FL, USA; Pittsburgh Pirates catcher Aaron McKeithan (92) poses for a photo during media day at Pirate City. Mandatory Credit: Kim Klement Neitzel-Imagn Images | Kim Klement Neitzel-Imagn Images

According to Tread Athletics, one of the top offseason training facilities for major and minor-leaguers, the Mariners recently signed former St. Louis Cardinals and Pittsburgh Pirates farmhand Aaron McKeithan to a minor-league deal.

McKeithan, 26, was the Cardinals' 16th-round pick in the 2021 draft out of UNC Charlotte. He appeared in 224 games for the Cardinals organization before getting selected in the Triple-A phase of the 2024 Rule 5 Draft by the Pirates.

After a tough season with the Double-A Altoona Curve, however, the Pirates reversed course and decided to release McKeithan in August. The Cardinals evidently didn't want him back at the time either, and he wound up finishing the season with the independent Gastonia Ghost Peppers of the independent Atlantic League.

The veteran pro catcher was a tough out for Pro Day pitchers all weekend. pic.twitter.com/k1lFhKmJba

— Tread Athletics (@TreadHQ) January 21, 2026

The Mariners know they probably aren't getting a future star in McKeithan, who has a career .257/.352/.334 slash line in the minors, with just 14 home runs in 265 games. But they evidently liked what they saw at Tread's recent pro day, and they had a fairly obvious need to address.

Not only did Ford leave via trade, but the Mariners lost big-league backup catcher Mitch Garver to free agency, while also trading prospect Luke Heyman to the Boston Red Sox.

Andrew Knizner will be Seattle's backup plan to Raleigh in 2026, but McKeithan gives them an interesting option for the future if the offseason adjustments he made prove to be transformational at the affiliated ball level.

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