How many additional rings will a QB bring?

The guys at Advanced NFL Stats have turned their high-wattage brains on converting the common statistic Win Probability Added (WPA) to Ring Probability Added (RPA). Despite the common misconception, Peyton Manning does very well in their new statistic:

The results are not hugely surprising. Brady leads the way with +1.38 RPA, followed by the Manning brothers, Roethlisberger and Brees – the winners of 5 of the last 6 Superbowls.