Summary
Despite Ojeleye having some promising moments over the course of his four-year career, including getting minutes for some conference finals teams, he just hasn't developed his offensive game enough to become a reliable rotational piece. Ojeleye has gotten to above-average from three-point range over the last two seasons, but it's on low volume, and he normally has to be wide open with his feet set in order to let it fly. He doesn't have any playmaking or off-the-dribble game.
 
On defense, Ojeleye is as strong as any wing, and can therefore hang with some of the elite wings in the NBA. However, he's not quick enough to be an elite defender, and doesn't provide rim protection in the way that someone like Draymond Green was able to do at his size. If he can improve his defensive positional awareness to provide better rim protection, teams may be interested in him as a small-ball center.
 
Since Ojeleye is already 26 though, teams may think he "is what he is" at this point, and may not have a ton of interest.
 
Cap Considerations
Ojeleye will be an unrestricted free agent with a $1.7 million cap hold and full Bird Rights, meaning the Celtics will have no restrictions on re-signing him.
 
Other teams will have multiple ways to sign Ojeleye as even teams without cap space could possibly use any of the Non-Taxpayer MLE, Taxpayer MLE, or possibly even the Room MLE or Bi-Annual Exception to sign him. There's also a chance that Ojeleye ends up settling for the minimum.