Rays manager Kevin Cash said Tuesday that McClanahan (forearm) is "highly unlikely" to pitch again this season, Jeff Passan of ESPN.com reports.
McClanahan landed on the 15-day injured list last week due to left forearm tightness and he has since visited a number of specialists in an attempt to get to the root of the issue. Cash told reporters that surgery is a possibility for the 26-year-old ace, who had pitched to an 11-2 record, 3.29 ERA, 1.18 WHIP and 121:41 K:BB through 115 innings (21 starts) this season. It's the biggest blow yet to a Tampa Bay pitching staff that has been ravaged by injuries to key starters.