Before Bryce Harper was the top pick in the Major League Baseball draft, before he signed the sport's biggest contract ever for a first-year pro, he gambled his future on one make-or-break season. The Las Vegas High School sophomore already had dominated the competition like Mickey Mantle on the playground and appeared on the cover of Sports Illustrated , which dubbed him the "most exciting prodigy since LeBron James." Seeking greater tests as a hitter,...