Crabtree was born on November 3, 1944, in Monessen, Pennsylvania, the son of a white father and African American mother.

[2] He attended Monessen High School, playing football under coach Joe Gladys.

He was one of the key players on Monessen's 1961 Western Pennsylvania Interscholastic Athletic League (WPIAL) championship team that won 11 games.

Teammates Doug Crusan, Bill Malinchak and Sam Havrilak would also go on to play in the NFL.

Crabtree was also a standout player of the school's basketball team, and played baseball as well.

[4][6] In 1998, Crabtree was inducted into the Mid Mon Valley Sports Hall of Fame.

[11] He also started every game for Denver the following year, improving his yards per reception average to 17.2, and again catching five touchdown passes.

[13] Eric had the nickname "E-Tree" while on the Broncos, and roomed with future Pro Football Hall of Fame running back Floyd Little.

[3][2] In later years, however, he suffered from severe depression, and became a member of a class-action lawsuit by former players against the NFL over the effects of concussions and repeated head trauma.