In general, these guys are such athletic freaks now, that they never learned to read a defense or really learned the game. They didn’t have to.
The QBs today only know the current way of playing (since 2004)…so it’s like playing on “Hard” mode. Brady, Manning etc., played on “Ultra Hard” mode to start their careers. Rules changes made it feel like “normal” mode.
Defensive players in today’s game are better than when Manning/Brady played because they play effectively even WITH all the handcuffs on defenders. They never had the old rules so there was no adjustment. The rule changes were from 19 years ago. Most top shelf defenders were somewhere between Pee Wee and middle school football at that point. Some guys were too young even for Pee Wee 19 years ago. All they know is modern ball so this feels normal for them.
TL;DR - old QBs had an advantage with the rule switch 19 years ago but modern QBs don’t have the advantage since modern defensive players only know one way to play
