Furbush has given up four earned runs in six innings with Tacoma and struck out seven while getting progressively stronger over his past few outings. He needed just 18 pitches in his two innings on Tuesday.
"Yeah, he's getting closer," manager Eric Wedge said on Wednesday. "There's nothing I can really say beyond that. He went two innings, and he actually was so efficient, we had him throw another 15 pitches in the bullpen to get him up over 30. He felt good, looked good."
With the off-day on Thursday, it would make sense for the Mariners to have Furbush fly back to Seattle and rejoin the club on Friday if he's ready. But a roster move would be needed to create an opening for him, so no announcement will be forthcoming until that decision is made.
Furbush went on the disabled list after feeling a strain in his shoulder after facing one batter in Kansas City on July 17. He has been one of the team's top relievers, going 4-2 with a 2.17 ERA in 37 1/3 innings, with 47 strikeouts, while holding left-handers to a .155 batting average.