What do you base your opinion that probability says its highly unlikely? What numbers support that position?
We just gave you 3 or 4 HoF QBs, one that is arguably the GOAT, that developed under defensive head coaches. And at least two of them won Super Bowls with their defensive HC in charge. And one of them won 7 Super Bowls. And Matt Ryan would have one if they had not blown a 28-3 lead to another QB that was developed by a defensive HC.