Matt Moore's changeup has caused a lot of trouble for hitters this season.
Now it's even a problem for Moore, Tampa Bay's All-Star pitcher who was put on the 15-day disabled list Wednesday with a sore left elbow.
Moore will miss one or two starts. The Rays are calling the move precautionary.
Moore is 14-3 with a 3.41 ERA in 21 starts. The Rays made the move while leading the AL East, and called up infielder Ryan Roberts from Triple-A Durham.
"If this was the playoffs or some situation that called for me to be out there, I think without doubt that I could do it," Moore said. "But there's just no reason for us to push things right now."
Manager Joe Maddon said the injury "wasn't anything awful, certainly a little more sore than he's accustomed to."
Moore left Sunday's start against the New York Yankees after just five innings.
"I think the second inning is when I started to feel it. But only on changeups, which is part of the reason why I stayed in at the game as long as I did, just mostly with fastballs and curveballs," he said.
Said Maddon: "That'll happen where guys will get sore on a certain pitch, and then if they don't throw it they stop being sore."
"But the changeup's a big pitch for him, so we wanted him to get that back," he said.
The 24-year-old left-hander is tied for second in the American League in wins and winning percentage (.824) and third in opposing batting average (.212).
"Anytime you're dealing with a pitcher and his arm, you're going to have some degree of concern, but everyone feels really good about it. So does Matt," Rays executive vice-president of baseball operations Andrew Friedman said.
"We're being overly cautious right now. The (upcoming) off-days afford us an opportunity to do that, and we're going to make sure that he's 100 per cent healthy when we put him back out there," he said.
Moore will be eligible to return on Aug. 13.
"I'm really not concerned about it for a couple reasons," he said. "I had an MRI to make sure that structurally everything is still intact, which it is. This a little hot spot so we're going to take our time, treat it properly, and make sure that I'll be there later in the season."