[8] After spending his freshman year at Cardinal Ritter College Prep High School,[4] he moved to Christian Brothers College High School, where he won a Missouri state title with future NBA player Larry Hughes as a senior in 1997.
[9][10] Tatum attempted to join the Saint Louis Billikens of the Conference USA for the 1997–98 season, but the National Collegiate Athletic Association (NCAA) ruled him ineligible for academic reasons.
[11] He failed to score high enough on the ACT and was subsequently diagnosed by a psychologist with a disorder that involved severe anxiety while taking tests.
[14] In the 1999–2000 season, Tatum averaged 8.3 points, 6.0 rebounds and 1.1 assists in 24.5 minutes in 32 games, including 16 starts.
[15][16] His NCAA eligibility subsequently expired and he had to join a National Association of Intercollegiate Athletics (NAIA) program to complete his collegiate career.
[19] He helped the team win the Promotiedivisie championship, which earned them promotion to the first-tiered Dutch Basketball League (DBL).
[22] In 2007, Tatum was appointed head coach of the Soldan High School boys' basketball team.
[23] In 2013, Tatum returned to Christian Brothers College High School, this time as head coach of the boys' basketball team.
[29] On November 14, 2023, he was promoted to interim head coach when Jacob Jackomas was fired after the Hawks started the season with a 2–7 record.
[30][31] Tatum guided the Hawks to seven victories in his first nine games as coach,[32] going on to lead them to a fourth-place finish and a 14–14 record.
[34] On February 22, 2024, prior to the Hawks' playoff campaign, Tatum signed a three-year deal with Illawarra to continue as permanent head coach.
[35][36][37][38] He helped the Hawks reach the semi-finals with a victory in the play-in game against the New Zealand Breakers.
[43][44] It marked the Hawks' first ever top-of-the-ladder finish in the club's 46-year history [45] Tatum was subsequently named NBL Coach of the Year.