Holtmann, the former coach at Gardner-Webb and Butler, replaced Thad Matta, who coached at Ohio State for 13 years. Friday's game was his 200th as a head coach, and Bates-Diop made sure Holtmann's debut with Ohio State was a success.
Bates-Diop, who played in only nine games last season after averaging 11.8 points and 6.4 rebounds per game as a sophomore, went 9-for-12 from the field and pulled down 11 rebounds Friday.
And he got plenty of help.
Kaleb Wesson wasn't the only freshman who distinguished himself in his first game for Ohio State. Guard Musa Jallow provided some firepower off the Buckeyes bench, scoring 11 points.
Forward Koby Thomas and guard Matty McConnell each scored 22 points for the Colonials. No other player for Robert Morris scored more than five points as Ohio State held the Colonials to 23-for-65 from the field (35.4 percent).
The Buckeyes trailed only very early in the game and took a 7-6 lead on guard Kam Williams' 3-point jumper. Kaleb and older brother, sophomore Andre Wesson, each scored five points as Ohio State went on an 18-5 run in the next six minutes to take control.
Thomas' 3-pointer cut the Colonials' deficit to 28-19 at the 8:35 mark of the first half, but then the Buckeyes outscored Robert Morris 15-5 and coasted to a 46-26 halftime lead.
Center Micah Potter scored six early second-half points as Ohio State opened up a 25-point lead. The lead grew to 30 at 73-43 on a dunk by Jallow.
Ohio State will host Radford on Sunday while Robert Morris travels to Phoenix to play the Grand Canyon Antelopes on Monday.