The A's lost a depth arm on Friday.
After being designated for assignment by Oakland on Wednesday, right-handed pitcher Cesar Valdez was claimed off waivers by the Toronto Blue Jays.
Valdez, 32, made four appearances for the A's this season including one start and posted a 9.64 ERA.
During his time with Triple-A Nashville this season, Valdez made two starts and had a 2.70 ERA in 10 innings pitched.
Toronto will option Valdez to Triple-A Buffalo.
Valdez is the second Bay Area pitcher to be claimed by Toronto this week. The Blue Jays claimed former Giants reliever Neil Ramirez on Thursday.