It's always difficult to compare players across eras, and at no place is the discrepancy more complicated than at quarterback. Many traditional quarterback statistics such as completion percentage, passing yards and touchdown-to-interception ratio, have risen significantly over the past few decades. On the other hand, quarterbacks are starting at younger ages now than ever before, a combination of rising salaries for rookies and the NFL's decision to allow players just three years removed from high school to enter the draft. Matthew Stafford and Josh Freeman are two of the youngest four players to throw for 300 yards in a game. And while Mark Sanchez and Sam Bradford aren't super young, they were thrown into the fire immediately. Both were opening day starters for their teams despite limited college experience: Sam Bradford threw at least 10 passes in only 29 games in college; Sanchez hit that number in just 16 games.
In some ways, the effects can cancel out. Maybe a 24-year-old quarterback who sat on the bench for 2 seasons but played in the '70s is similar to a 21-year-old rookie starter in 2009. But it's important to compare apples to apples, or at least to recognize which fruits you're comparing. For that reason, I'm going to take a look at how Bradford, Sanchez and Freeman are doing -- era-adjusted, of course -- in three different ways: how they played by experience, by age, and by seasons starting.
First, against which quarterbacks should we compare these three (and Matthew Stafford)? I took 30 or so of the best and most famous since the merger. Why the best? If these guys can hold their own against the all-time greats, then for all their criticism, their potential should still look strong. Here's the full list of quarterbacks:
