Ohio State's issue isn't the defensive coordinator. It is their recruiting and development on the defensive side of the ball. They have become soft on defense over the last couple years. They don't have an elite DE like they have had for over a decade, with Nick Bosa, Joey Bosa, Chase Young, etc. They don't have the lock down CB's they have had for the past decade plus -- they don't have an Okudah, Lattimore, Conley, Arnette, Ward, etc. to lock down half the field. The guys they have can punish the weaker teams, but anyone who can match talent and play physical bullies them.
With the absolutely ridiculous amount of talent they had on offense this year -- there is no chance they should have lost two games. Now they have to hope Egbuka and Fleming can fill the big shoes left by Wilson and Olave.