He credited video coordinator Kyle Davis with discovering Hookfin, who made the Cox Media Group Ohio area Division I third team after scoring 14.2 points per game as a senior for the Warriors last year.
“Really about a month and a half ago, I said, 'Hey, keep your eye open for someone, as you're talking to people,' and he brought his name,” Holtmann said. “Harrison came and practiced. He still is working through the normal eligibility process but he is a current member of our grown as a walk-on.”
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Hookfin shot 52.2 percent from the floor, including 34.3 percent from 3-point range, while grabbing 7.1 rebounds per game last season.
He gives Ohio State more depth, something that became a greater need after the transfer of big man Micah Potter shortly before the season and a recent injury to starting forward Kyle Young.
Ohio State started 13-1 before losing five in a row.
The Buckeyes snapped their losing streak with a 70-60 win at Nebraska on Saturday, and they head to Michigan to take on the fifth-ranked Wolverines on Tuesday night on ESPN2 at 9 p.m.
Justin Ahrens, a freshman from Versailles, is averaging 1.7 points and 1.1 rebounds in 12 games for the Buckeyes.
He has seen an uptick in playing time recently, getting 10 minutes or more in three of the last four games.
He scored six points in a loss at Iowa on Jan. 12 and six points in a home loss to Purdue on Jan. 23, hitting a pair of 3s in both games.