The fact you want numbers is silly. You go back around 30 years to name a few when the league and its rules were vastly different. Roethlisberger was developed by Cower more then Tomlin, but the point still stands. Name 1 franchise QB developed in the last 10 years by a defensive head coach. Name 1 defensive head coach that has gone to the superbowl in the last 10 years.
The simple truth is the trend is that offensive head coaches develop franchise QBs, and offensive head coaches win superbowls for the last 10 or so years. People who invest against the trend in stocks, crypto, real estate etc end up in bankruptcy far more often then not. The probabilities are the same here.
Never bet against the trend. Glenn coming here will likely not end up in the superbowl for his tenure here. If I gambled, thats where the smart money bet would be based on trends.