Whalen was recalled from Triple-A Tacoma on Wednesday.
With all the injury woes plaguing the Mariners' pitching staff, Whalen will be summoned from the minors to provide some fresh innings. He seems like a candidate to fill the long-relief role in the bullpen after Emilio Pagan was optioned to Triple-A in a corresponding move, but as per Bob Dutton of The News Tribune, Whalen is also a candidate to start Saturday's game versus the Red Sox.