Jason Heyward was one of the top players in baseball early in his career, with a Hall of Fame trajectory over his first six seasons with Atlanta and St. Louis. Through age 25, his 29.8 career WAR was among the baseball legends to start a career, surrounded by guys like Babe Ruth, Lou Gehrig, and Barry Bonds.
Things immediately went downhill when he signed an eight-year deal with the Cubs prior to the 2016 season. He had been 14 percent better than league average offensively with elite outfield defense in his first six years; in his seven years in Chicago, he was 14 percent worse than average and merely good defensively, leading the Cubs to release him with a year left on his contract.