Seattle designated Baek for assignment May 21, after he went 0-1 with a 5.40 ERA in 10 games, mostly as a long reliever. Baek, who turns 28 on Thursday, was signed by the Mariners as a free agent in 1998 and re-signed as a minor league free agent in 2006. He has a career major league record of 10-9 in 37 games.
The 26-year-old Wells has allowed two runs in two games this month for San Diego in his major league debut. He had nine saves for Triple-A Portland before his callup. He potentially could start for Seattle -- San Diego shifted him to the bullpen only last season. The Padres selected Wells in the 31st round of the 2002 draft.
Seattle optioned Wells to Triple-A Tacoma.