A's Rookie Pitcher Mason Miller Sidelined with Mild UCL Sprain.

Oakland A's rookie starter Mason Miller has been diagnosed with a mild sprain of the ulnar collateral ligament in his throwing elbow and will be shut down from throwing for an indeterminate period of time until he's no longer feeling discomfort. Miller will avoid surgery but is likely to be out of action for an extended stretch. The 24-year-old had shown well early on, tallying 21 2/3 innings of 3.38 ERA ball over his first four starts, striking out more than a quarter of opposing hitters.