When Shelden Williams was a freshman his offensive talent was extremely low his frosh year at Duke. He traveled nearly every time he got the ball. I assume he was still more talented than Obekpa, never having seen him play, based on all accounts, since Shelden averaged 8 points his frosh year. That said, Shelden was a beast rebounder/shot blocker. By his senior year, he averaged 19 a game and was an offensive force in college...of course until his offensive deficiencies were totally exposed in the NBA. That said, just using him as an example of how a top defensive player that is EXTREMELY raw offensively can make an impact immediately, and also can become quite talented offensively with the right coaching. Obekpa would be a great signing!
Even at the NBA level, look at what Tyson Chandler did for the Knicks defense basically singlehandedly. Was his contribution not paramount to the Knicks (relative) success this year? Tyson has no offensive skillset to speak of, he's got no post moves, no face up moves, no baby hook, just a sick rebounder who can flush it on an alleyoop. Think about how many extra possessions the Knicks had because Chandler tipped a ball back out on offense that he didn't even get credit for boarding. Blocked shots and offensive rebounds are demoralizing for the other team. If big Chris can bring those 2 things, then I don't give a shit if he doesn't attempt one field goal outside of a put back all season.