Arrieta announced Monday on Barstool Sports' "Pardon My Take" podcast that he's decided to retire after a 12-year career in the big leagues, ESPN.com reports. "Well, I haven't signed the papers, man, but I'm done. It's time for me to step away from the game," Arrieta said. "At some point the uniform goes to somebody else and it's just my time, really."

Arrieta (groin) was designated for assignment by the Padres on Tuesday.

Arrieta was diagnosed with a right adductor strain after leaving Sunday's start against the Cardinals.

Arrieta exited Sunday's game against the Cardinals after a third of an inning with an apparent injury, Katie Woo of The Athletic reports.

Arrieta (5-13) was tagged with the loss Tuesday against the Giants after allowing three runs on five hits and two walks while fanning three across 3.2 innings.

Arrieta (hamstring) was reinstated from the 10-day injured list prior to Friday's start against the Astros, Jeff Sanders of The San Diego Union-Tribune reports.

Manager Jayce Tingler said he expects Arrieta (hamstring) to start Friday against the Astros, AJ Cassavell of MLB.com reports.

Arrieta (hamstring) is expected to be activated for this weekend's series versus Houston, Bob Nightengale of USA Today reports.

Arrieta (hamstring) threw a bullpen session Saturday and could return to the Padres in early September, per MLB.com.

Arrieta was placed on the 10-day injured list with a left hamstring strain Friday, retroactive to Aug. 19.