Seems evident he is not going to get an OC job (at least not at OSU) so why not come back to a place he liked a lot.

blessing is going to better prepare him to get a job promotion than would be making a second lateral change as a position coach at this level for a head coach who already passed him over.

If he's still looking to move up, returning to ND seems puzzling unless his relationship with Day is strained. Or unless he gets some assurance he'll be considered for an OC job when Long likely leaves soon. Or if he gets a co-coordinator title. But with Quinn on staff, that doesn't seem like an attractive place to advance his career.

That said, if his ambitions have changed and he wants to just settle into a position coach job at a place he likes, then sure it makes sense.

He may question his long-term standing on Day's staff. In a situation like this, a new coach will often keep most of the staff in tact for the first year to avoid too much turnover, and then replace guys on the staff with his own guys after a year or two.