When the Yankees called up Kevin Maas in June 1990, he electrified fans by blasting 10 home runs in just 77 at-bats—the fastest ever to reach that mark. He hit numbers 9 and 10 against the Tigers on August 2, and finished his partial rookie season with 21 homers and was runner-up for Rookie of the Year. Maas added 23 more the next year, but his star quickly dimmed, leaving him with 65 career home runs and a place in baseball’s “what could have been” stories.