The NBA only has record of one Bill Melchionni, who played for Philly from 1966-68 per his stats page. His Wikipedia page indicates that he was 9 in 1953, never played for the Fort Wayne Pistons, and never won a Rookie of the Year award in any league.
Basketball Reference shows no one named Melchionni on Fort Wayne's roster in 1952-53, but there was a Monk Meineke (Donald E. Meineke).
In short, ESPN is wrong. I see the error on this page. If you go to his ESPN stats page, you see that he was born in 1944. He would have been the first 9-year-old to win Rookie of the Year.