Strahm is dealing with mild biceps tendinitis, Rustin Dodd of the Kansas City Star reports.
It was puzzling that Strahm had not been used in September after punching out 20 batters in 15.1 scoreless frames in August, but the reason for his lack of usage is now clear. While Strahm has not pitched in over a week, the Royals are hopeful that he will be available out of the bullpen again before their current series with the Twins comes to a close.