The belief among Capps' doctors is that thoracic outlet syndrome played a part in the formation of the blood clot. Capps, who has returned to his home in the Seattle area, will consult with doctors again before finalizing the decision to have surgery.
"It's just another unfortunate break for someone who's fought very hard to be on a baseball field for a very long period of time," said Padres manager Andy Green. "But I do think it probably makes him feel pretty good that they think they can fix what's happened."
Capps had Tommy John surgery in March 2016, before he was traded from Miami to San Diego that July. In 11 appearances for the Padres, he posted a 6.57 ERA in 12 1/3 innings -- though he allowed only one run and two hits over the last 7 2/3.
Given the nature of his quirky hop-step delivery, it took Capps some time to hone his mechanics following surgery. In his final six outings, he appeared to be regaining his form, despite the fact that his fastball velocity -- once in the high 90s -- averaged 93 mph.
"The shoulder is solid, his health from a throwing perspective is very good," said Green. "You would think his road back would be quicker. I think every expectation is he would be ready to pitch in Spring Training next year."
• The Padres are in the process of finalizing winter ball plans for several players, though they haven't yet made any announcements. Rookie catcher Luis Torrens, a Rule 5 pick, was the only name Green gave when asked who those players might be. Torrens is a logical candidate to get some extra playing time, as he's received only 705 career at-bats in the five seasons since he signed a pro contract, due largely to injury.
AJ Cassavell covers the Padres for MLB.com. Follow him on Twitter @ajcassavell. This story was not subject to the approval of Major League Baseball or its clubs.