"He's getting better," McClendon said. "He was set back a little, but he is going to do some bullpen sessions and hopefully he'll pass the tests and be ready to go [soon]."
The Mariners could use the left-hander's proficiency in a bullpen that has struggled to duplicate last year's success. Furbush has a 2.08 ERA and 0.646 WHIP in 33 games, has stranded all 16 runners he's inherited and opposing batters are hitting just .122 against him.
McClendon said he wasn't sure when Furbush would be able to throw a simulated game situation against live hitters, which likely would be the final step before he's cleared to rejoin the club.
"We have to see if he passes these bullpen tests first and go from there," said McClendon. "The idea was that he was going to throw a sim game here [in Detroit], but he ain't here, so that's not going to happen."
• Several Mariners prospects played prime roles in the Pan Am Games, where Canada won the gold medal with a 7-6 win over Team USA on Sunday night in Toronto. Patrick Kivlehan (Triple-A Tacoma) hit .342 during the 11-game tournament for the U.S. squad, while Tyler O'Neill (Class-A Bakersfield) had three home runs for Canada. Jordy Lara (Double-A Jackson) had a home run for the Dominican Republic.
Greg Johns is a reporter for MLB.com. Follow him on Twitter @GregJohnsMLB, read his Mariners Musings blog, and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.