Tampa Bay Rays ace left-hander Shane McClanahan was placed on the 15-day injured list on Saturday, one day after exiting his second straight start due to mid-back tightness.
McClanahan departed after giving up four runs and five hits over three innings on Friday night against the Seattle Mariners. He left after 3 2/3 innings against the Kansas City Royals on June 22.
The timing of the move will prevent McClanahan from pitching in the All-Star Game in Seattle on July 11. He was in the running to start the Midsummer Classic for the second straight year.
"I really would not put any of our thoughts into any All-Star anything," Rays manager Kevin Cash told reporters prior to Saturday's game against the Mariners. "We want our players to, if they are recognized and good enough to be All-Stars, that's a totally separate discussion. We've got to prioritize his health above everything."
McClanahan (11-1) entered Saturday with the most victories in the majors and the fifth best ERA (2.53). He has 101 strikeouts in 96 innings.
McClanahan, 26, was mystified with the back issues when he met with reporters following Friday's game.
"I mean, I don't think anyone's really overly too concerned," McClanahan said. "I mean, my arm felt really good. I was throwing 99 mph, so that was good to see, but obviously, something is not 100 percent right, and we're going to do whatever we've got to do to get that right."
In 70 career starts over parts of three seasons, McClanahan is 33-15 with a 2.82 ERA and 436 strikeouts in 385 2/3 innings.
The Rays recalled left-hander Jalen Beeks from Triple-A Durham in a corresponding move. Beeks, 29, is 2-3 with a 5.82 ERA in 25 appearances (seven starts) for Tampa Bay this season.
More must-reads: