At 22, Bradley Constant can relate to the 15-year-old he's playing in NBC comedy "Young Rock," which debuts Tuesday. Both he and Dwayne "The Rock" Johnson come from supportive families; both have tight relationships with their moms. Both grew up with athletes around, and both are focused on careers in show business. Both dream big, and take decisive action to make those visions come true. Constant, a Tuscaloosa born-and-raised actor, is getting his big break playing that 15-year old version of Johnson, who his family called "Dewey." Though he performed in a few musicals in elementary school, Constant was more interested in baseball and basketball than acting, until he was sidelined.