Tom Brady, Drew Brees and Peyton Manning are widely accepted as three of the greatest quarterbacks in NFL history. They excelled in many areas of the game, but according to NFL analyst Greg Cosell, their era of greatness was defined by how they manipulated defenses in the pre-snap process.Cosell recently appeared on an episode of the "Ross Tucker Podcast" to discuss how most of the modern quarterbacks approach the game much differently. He explained that only a couple of today's quarterbacks can be labeled as pre-snap operators, while most of them do the majority of their work post-snap.Cosell said:"The era of the Bradys, the Brees, and Mannings ... guys who were pre-snap operators, there might be two guys in the league like that today ... Joe Burrow and Aaron Rodgers.""Most quarterbacks now are what we call post-snap operators. They're basically taking the snap and then figuring out where to throw the ball based on what they see ... Brock Purdy is one of those guys, he sees the field intuitively. He is an elite processor, which allows him to throw with high-level anticipation."What made legends like Peyton Manning, Tom Brady and Drew Brees so difficult to defend is that they often knew where they were going with the football before they even snapped the ball. It wasn't necessarily pre-determined in the huddle, but they were all masters of reading the defense and knowing where the weakness was before ever even snapping the ball.Cosell acknowledged this and explained that, other than Joe Burrow and Aaron Rodgers, it's hard to find any modern quarterbacks that operate in this way.NFL QBs today who excel as post-snap operatorsBrock PurdyGreg Cosell used the example of Brock Purdy when describing NFL quarterbacks who excel as post-snap operators. He explained that he has an excellent ability to quickly process what the defense is doing and make a prompt decision on where to go with the football. He also added that his tandem with head coach Kyle Shanahan is ideal for his style of quarterbacking.Other obvious examples include elite playmakers like Patrick Mahomes and Josh Allen. They have established themselves as some of the most productive quarterbacks in NFL history and have mostly done so in their off-script plays following the snap. This suggests that while the new era is certainly different in its approach compared to previous legends, it doesn't mean it's a worse strategy.