Brad Penner-USA TODAY Sports

The Tampa Bay Rays placed All-Star left-hander Shane McClanahan on the 15-day injured list on Thursday after he experienced forearm tightness in his pitching arm during his start one night earlier against the New York Yankees.

The Rays, idle on Thursday, sent McClanahan back to Florida for further testing and evaluation.

McClanahan, who was activated from his prior IL stint on July 17, told reporters after suffering the loss in Wednesday's 7-2 defeat at New York that the outside part of his forearm "just kind of got tight, kind of grabbed on me a little bit" when warming up before the fourth inning. He alerted Rays manager Kevin Cash of the issue and was pulled after throwing a scoreless fourth inning.

The 26-year-old has not looked like his All-Star self since returning over two weeks ago. In his four starts since the end of his first IL trip, McClanahan has gone 0-1 with a 7.11 ERA, averaging fewer than five innings per start.

"It just grabbed and wouldn't let go, and I was like, ‘This is kind of interesting,' " McClanahan said afterward, per MLB.com. "I got through the fourth and made note of it to him. I told him (Cash), I said, 'Hey, listen, this happened. I can keep going.' And obviously, we decided to err on the side of caution.

"I'm not going to speculate. I'm not going to make any assumptions. We're just going to take it day by day and see what comes up. It's one of those times in my career where you either put your head down and hide or keep your chest up and keep working."

Though his season numbers still look stellar (11-2, 3.29 ERA in 21 starts), McClanahan had been tied for the major-league lead with 11 wins and had baseball's best ERA (2.53) until his prior IL stint -- which was caused by recurring back issues that forced him to shorten a pair of starts.

The Rays, whose three-game winning streak was snapped in the loss to the Yankees, begin the final series of a nine-game road trip on Friday in the first of three games against the Detroit Tigers.

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