Whitley has been told by a doctor that he'll need Tommy John surgery, Mark Berman of KRIV Fox 26 reports.
Whitley experienced some arm soreness during a recent simulated game and has since been diagnosed with a right UCL sprain, per Chandler Rome of the Houston Chronicle. It's the latest in a long line of setbacks for the talented 23-year-old, who's thrown just 86 innings since the start of the 2018 season due to a suspension and multiple injuries. It had looked as though he was on the doorstep of making his big-league debut, especially after Framber Valdez fractured his finger, but it now looks as if he won't pitch in any capacity until the middle of next year. He'll get a second opinion, the results of which should be known within a few days, before going through with the procedure.