It's always difficult to compare players from different eras, too many people just look at stats and that's not really a good comparison. The modern era/current QB's have a huge advantage because of the NFL rules that continually promote more passing and more games played to compile those numbers. It was much harder to compile those gaudy passing stats back in the day, DB's and LB's didn't have the handcuffs they have now when playing receivers. How many modern era WR's or TE's would get alligator arms going over the middle with Jack Ham or Butkus waiting to hit them, under the less offense friendly modern rules, that receiver is getting laid out whether he touches the ball or not. It doesn't matter if the ball is even being thrown his way, he's getting hit just for being there, no flags, just another incompletion and hope he didn't get his bell rung too bad. With all the rules that now protect QB's, late hits, hits to the head, hits below the knees, roughing the QB, tuck rules etc. how many of today's great QB's would have long enough careers to compile those stats. The kind of calls and protection afforded to the Bradys and Mannings of our world wouldn't have been extended back then, outside of pulling a gun and shooting a QB they didn't get those kind of calls. I'm not saying the modern QB's aren't tough enough, but hits like that shorten careers and you can never say if one of their careers would have ended prematurely due to injury. Another consideration is the improvement of modern medicine, the type of treatment and surgical care common today was just science fiction 20+ years ago. I'm not saying the great modern QB's still wouldn't have been great players in another era, just don't discount what it took to be a great QB back in the day.