The Red Sox outrighted Guerrero to Triple-A Worcester on Thursday, Chris Cotillo of MassLive.com reports.
Guerrero had been designated for assignment last week, and he will remain in the organization after somewhat surprisingly clearing waivers. The hard-throwing reliever has posted a 2.63 ERA but a problematic 19:16 K:BB across 27.1 frames covering parts of two major-league seasons.