Vargas (elbow) threw a successful bullpen session Sunday, Matthew DeFranks of FOX Sports Kansas City reports. Vargas, who was placed on the DL back on May 8, was able to mix in all his pitches and said he felt nothing more than the usual soreness after the vigorous session. It doesn't appear that Vargas is on track to return to the Royals' rotation this week, but manager Ned Yost doesn't believe the lefty will need a rehab assignment before his activation. Once he demonstrates he's fully healthy with a few more side sessions, Vargas would likely replace either Chris Young or the struggling Danny Duffy on the starting staff.