The Mariners replaced Pagan by recalling right-hander Rob Whalen from the Rainiers in their latest move to keep fresh arms in a bullpen that must support an injury-depleted rotation.
It is the second such recall this season for Whalen, who spent one day — May 5 — in the majors before getting sent back to Tacoma without appearing in a game.
"He’ll be available out the bullpen the next couple of nights," manager Scott Servais said. "He could start for us over the weekend. We need a starter on Saturday (in Boston)."
Whalen, 23, was 1-2 with a 6.57 ERA last season in five starts for Atlanta. The Mariners acquired him with pitcher Max Povse in a Nov. 28 trade for outfielder Alex Jackson and pitcher Tyler Pike.
Whalen began the season on the disabled list because of shoulder inflammation. He was activated April 27 and optioned to Tacoma, where he is 0-2 with a 4.09 ERA in four starts.
Pagan, 26, was recalled Monday from Tacoma, but his four innings Tuesday effectively rendered him unavailable for the next few days. It was also his second recall; Pagan spent four days in the big leagues earlier in the month.
"He really helped himself as far as raising himself on the depth chart," Servais said. "The key for him, as we talked the last time he was here, is he’s got to get his secondary pitch over the plate.
"He had a really good slider (Tuesday) night. He executed it against a very good lineup."
Bob Dutton: @TNT_Mariners