Arrieta (groin) was designated for assignment by the Padres on Tuesday.
Arrieta exited Sunday's start against the Cardinals with a strained right groin, and he won't make another start for San Diego. The 35-year-old was picked up in mid-August after being let go by the Cubs, and he surrendered 15 runs on 18 hits in 12.1 innings across his four starts with the Padres while also spending some time on the injured list.