Arrieta has been working out with Double-A Bowie the past two days after starting Triple-A Norfolk's season finale.
Arrieta was optioned to Norfolk on July 5 after going 3-9 with a 6.13 ERA in 18 starts for the Orioles.
He has pitched well in Triple-A. Over his last four starts there, he is 2-1 with an 1.82 ERA and 31 strikeouts and nine walks over 24 2/3 innings. Overall, Arrieta was 5-4 with a 4.02 ERA in 10 starts.
He was recalled for one day 10 days ago to provide a right-handed relief arm to replace Matt Lindstrom, who was traded to the Diamondbacks for Joe Saunders, but he didn’t pitch.
Orioles manager Buck Showalter said Tuesday that Arrieta’s strike-throwing in Norfolk has been the difference in his improvement. Arrieta will be used out of the bullpen, but he will also give the Orioles a starting option down the stretch run.