Standing 6-foot-3 and 163 pounds, Diaz is the definition of skinny, and scouts aren't sure how much weight he'll add because of his narrow frame. Diaz's body has pros and cons. His long arms allow him to whip the ball with surprising velocity. He sits in the 92-95 mph range and touched 97 twice in his first outing at Puerto Rico's annual Excellence Tournament in early May. But, like many tall, gangly pitchers, he has trouble coordinating his limbs, which leads to spotty control and an inconsistent curveball. He also hasn't used a changeup much. Taken together, those factors lead many scouts to believe he fits best as a power reliever in pro ball. Diaz is relatively new to pitching, having just started when he was 15 years old. His cousin, Jose Melendez, pitched in the big leagues for parts of five seasons in the 1990s for Seattle, San Diego and Boston.