The Red Sox placed Guerrero on the 15-day injured list Tuesday with right shoulder inflammation.
Guerrero was charged with three runs while recording only one out in Monday's win over the Mariners, and a day later he's now on the IL. Interim manager Chad Tracy said he's "very hopeful" Guerrero will be back when his 15 days are up, per Tim Healey of The Boston Globe. The 35-year-old has been a pleasant surprise in the Boston bullpen this season, collecting a 3.26 ERA and 36:7 K:BB over 38.2 frames.