The Angels recalled soft-tossing lefty Brad Mills from Triple-A Salt Lake to take Thompson's place on the roster, then sent Mills back after Saturday's 7-1 win over the Yankees in order to make room for Sunday's starter, Jerome Williams.
Thompson posted a 3.00 ERA in 54 innings last year, his first full season in the Majors, striking out 9.3 batters per nine innings and posting a 1.22 WHIP. But the 27-year-old right-hander struggled in tough spots, with opponents posting a .761 on-base plus slugging percentage against him in what Baseball-Reference.com refers to as high-leverage situations.
The Angels now have 10 days to waive, trade or release Thompson. With an average fastball velocity of 94 mph and a good curveball, Thompson is unlikely to make it through waivers unclaimed. But Angels manager Mike Scioscia said Thompson's stuff is "not as crisp as it was last year."
"He'll get that back," Scioscia said. "It's just right now, where we are, we don't have the time to use that one spot to get him where he needs to be."
With Mills back in the Minors, Hisanori Takahashi is the Angels' only lefty reliever until Scott Downs, out with a bruised right ankle, makes his way back.