As recent as the end of the 2011 season, talk amongst fans and analysts arose on whether or not Brees and/or Rodgers is a product of his system. To determine just which of them is a "System QB", we're going to have to look at some facts.
Rodgers entered the league in 2005, when he was drafted 24th by the Packers, picked to be the heir to then quarterback Brett Favre. Since then, he has become one of the league's most prolific passers, currently holding records for highest passer rating in a single season (122.5) and lowest interception percentage for quarterbacks during the regular season (1.80 percent), as well as being the NFL's all-time career leader in passer rating during both the regular season (104.1) and the post-season (105.5).
This isn't to say that Brees isn't a phenomenal quarterback. Since he's come into the league in 2001, he's had an equally illustrious career, breaking records for most passing yards in a season (5,476), highest completion percentage in a season (71.2 percent) and most completions in a season (468), just to name a few. However, we're not here to count records, we're here to look at facts; and the fact is: before Drew Brees came to the Saints, he was not the quarterback we all know him to be.
Before coming to New Orleans, Brees hadn't had a year in which he threw for more then 4,000 yards. In fact, whilst in San Diego, Brees only had one year in which he posted an above 95.0 passer rating. Whether it be Marques Colston, Devery Henderson, Lance Moore, or even Robert Meachem, Brees has always had a slew of receivers to throw the ball to en-route to becoming one of NFL's best quarterbacks.
Now, I know what you're all thinking: yes, Aaron Rodgers does have one of the best WR cores in the NFL, but no, not everyone on the team was always such a great receiver. From 2008-2010 (not counting the '10 Super Bowl run), only Greg Jennings and Donald Driver had more than 700 yards receiving for the year.
At the end of the day, both of these quarterbacks are amazing at what they do, and both will probably be in the MVP race for many seasons to come. However, when it comes to talk of who's a "system quarterback" and who isn't, well, I like to let the stats speak for themselves.