The blood clot was discovered following Vargas' start against Seattle on Monday, making his move to the disabled list retroactive to Tuesday. He will seek a second opinion at UCLA before considering surgery.
"You always want to keep pitching, but at the same time, I'd rather not have a blood clot in my shoulder," said Vargas, who was scheduled to start Saturday against the Pittsburgh Pirates. "If I was pitching and it came loose, then it could really cause some issues. So I'm definitely glad the staff recognized it and we got it taken care of and looked at, and we're going through the right channels."
Vargas is 6-4 with a 3.65 ERA in his first season with the Angels, who acquired him from the Mariners in the offseason. A few days before his last start, he noticed temperature differences in his pitching hand caused by circulation problems due to the clot.
"It doesn't affect the way I can throw the ball or anything like that," Vargas said. "It's just not letting blood travel like it should."
Jerome Williams will take Vargas' turn in the rotation Saturday against Pittsburgh. The Angels also selected the contract of right-hander Billy Buckner from Triple-A Salt Lake to fill Vargas' roster spot.
Williams got bumped out of the Angels' rotation recently despite going 5-2 with 3.14 ERA this season, making seven starts and 18 appearances. Williams was put in long relief instead of Joe Blanton (1-10, 5.62 ERA), who has improved in his last few starts despite his dismal record.
Buckner got his first major league victory since 2009 for the Angels last month, pitching five innings of two-hit ball in Kansas City. The 29-year-old hadn't pitched in the majors since 2010.