Blackburn was recalled from Oakland's alternate camp site Wednesday, Martin Gallegos of MLB.com reports.
Blackburn will provide the A's with a fresh bullpen arm after Tuesday's starter (Frankie Montas) recorded just five outs before exiting. The righty appeared in four games for the A's in 2019 and allowed 13 runs across 11 innings. James Kaprielian was optioned in a corresponding move.