Morse began his rehabilitation assignment at AAA Tacoma on July 22. In six games with the Rainiers, he hit .250 (6-for-24) with 1 double, 1 home run, 2 RBI, 2 walks and 6 strikeouts.
Morse has been on the disabled list since June 22 with a strained right quadriceps muscle. He saw limited action after suffering a right quad injury May 28 vs. the Padres, appearing in 11 of the Mariners 23 games (at DH, 1B or PH) prior to being placed on the DL.
For the season Morse is batting .251 (52x207) with 11 home runs and 23 RBI in 56 games.
Bay, 34, appeared in 68 games with Seattle this season, batting .204 (42-for-206) with 6 doubles, 11 home runs and 20 RBI.
Bay, who has played for San Diego (2003), Pittsburgh (2003-2008), Boston (2008-09), and the Mets (2010-2012), was signed by Seattle as a free agent on Dec. 12, 2012.
Seattle now has 10 days to trade, release or outright the contract of Bay to the minors.