Farquhar joins the Mariners for the fourth time this season, having posted a 6.23 ERA and 1.62 WHIP in 30 1/3 innings over 25 appearances. The 28-year-old pitched three games with the club in early July before being optioned back to Triple-A.
"I was told he's throwing extremely well and is close to being where he needs to be, so I wanted to get an eye on him and see where he is," Mariners manager Lloyd McClendon said. "We need him back to being the guy he's capable of being. He was a big part of our bullpen last year, and hopefully he's back on the right track."
Farquhar had a 2.66 ERA in 66 outings in 2014, but he hasn't been able to duplicate that this year.
"It's kind of been a little bit of everything," Farquhar said. "A little bit of bad luck. A lot of bit of bad pitches. Then getting put in those extended situations are always tough."
The 5-foot-9, 185-pounder from Florida is 1-1 with a 3.62 ERA in 32 1/3 innings over 22 appearances with Tacoma this season, including a 2.13 ERA and 13 strikeouts in 12 2/3 innings over his 10 games since being sent down the last time.
"I feel good. I just have to keep pitching like that," Farquhar said. "My cutter, fastball and curveball are where I want them. I haven't thrown as many changeups as I'd like, but that was my fourth-best pitch anyway."
Farquhar was pulled from Friday night's game in Tacoma, drove to his home on Mercer Island to pick up his belongings and caught an 11:20 p.m. PT red-eye flight through Detroit and arrived at Fenway Park in time to be available for Saturday's game.
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.