Thank you for posting this. Your chart points out that 2010, 2011, 2013, 2014, 2015 were really bad years to find your "franchise QB" in the first round. When I get the time I'm going to take a look at the other QB's in those classes just to see how they panned out or if any are still in the NFL
Your data does show that the higher a QB is drafted the more likely he is to have success. Still, QB evaluation is an inexact science. As someone noted at this time Brady, Wilson, Cousins, (and I'd add Dak Prescott to the list) are quality QB's and none of them were drafted before 3rd round. Kurt Warner is in the Hall of Fame. He was undrafted and had to spend time in inferior leagues before he was given a shot. Tony Romo had a respectable career and he was also undrafted. I think that's a reflection on the scouting process and not the players themselves. And sometimes the amount of fight and desire (which is immeasurable) you have inside overcomes any physical limitations a player might have.