Farrell was outrighted to Triple-A St. Paul on Friday, Aaron Gleeman of The Athletic reports.
Farrell finished the campaign as a member of the big-league bullpen, but he's been removed from the 40-man roster heading into the offseason. The 30-year-old made 20 appearances for Minnesota this year and had a 4.74 ERA, 1.66 WHIP and 25:13 K:BB over 24.2 innings.