Duffy (shoulder) threw another bullpen session Sunday, Andy McCullough of the Kansas City Star reports. Duffy has thrown twice in the last three days as he aims to work his way back from a sore shoulder. He'll be eligible to return from the DL on Monday, but the Royals could opt to wait a few additional days before bringing him back. It's not immediately clear what role Duffy will fill upon his activation, as the Royals have since returned Jason Vargas from the DL and continue to receive great work from Chris Young, which could close off Duffy's path to the rotation at least temporarily. Duffy isn't helped by the fact he struggled in his first eight starts before being sidelined, as he posted a 5.87 ERA and 1.69 WHIP across 38.1 innings.