Diaz signed a minor-league contract with the Astros on Saturday, Chandler Rome of The Athletic reports.
Diaz was let go by the A's last week after posting a .236 OPS in 30 major-league plate appearances, but he'll now receive another opportunity with the Astros. He'll report to the team's complex in Florida in order to work on his mechanics before likely moving to Triple-A Sugar Land to fill in as organizational depth.