Tom Brady's Legacy: Can We Call Him the Greatest of All Time?

Since Super Bowl XLIX ended with a Patriots victory, there has been much debate over Tom Brady's legacy. New England has now won four Super Bowls over the past decade-and-a-half with Brady under center, and thus comes the deliberation over if, with these victories, Brady is now the best quarterback of all time.

For the context of this debate, let’s throw away the notion of quarterback wins. It's simply not a statistic of any meaning. Quarterback play certainly has a massive contribution to NFL teams success, but the idea that quarterbacks alone contribute enough to deserve merit for an entire team's victory just isn't realistic.

Indeed, the Patriots have won four Super Bowls with Tom Brady as quarterback, but the “best quarterback of all time” debate shouldn’t begin with semantics of Super Bowl victories. It should come down to simply how well that quarterback plays.

Thankfully, we can separate the idea of statistical contribution from the falsity of “quarterback wins” with advanced metrics. Where does Brady land in all of this? Is he the best, or do his critics have merit by calling him a clutch game manager?

Unquestioned Regular Season Production?

For background, I will be using our Net Expected Points (NEP) metric to frame this article. With quarterbacks, incompletions and interceptions matter a lot in terms of NEP (and, quite frankly, play on the field). If a quarterback throws an interception on 3rd-and-27, it doesn't harm his team as much as an interception thrown on 2nd-and-Goal inside of the red zone. One throw subtracts more NEP -- is more impactful -- to the player's total than the other. On the surface, those interceptions would be viewed as equal but, thanks to NEP, all turnovers are not created equally.

To devise Brady’s success over his 15-year career, I didn’t think it would be enough to form a concrete argument to just show his relative Passing NEP ranking over the years. Even though it may not seem like it at times, quarterback play has vastly improved over the past 15 seasons, so it's not really an apples-to-apples comparison.

So, in order to prorate Brady’s season-by-season NEP, I created two additional columns called “Average NEP Differential” and “Top-5 Differential”. The “Average NEP” and “Top-5 NEP” differentials give us a barometer of how far below or above Tom Brady was among all quarterbacks with at least 160 drop backs (10 or more per game) for a given year. Pluses (+) indicate his on-field performance was above the relative seasons trend and minuses (-) indicate it was below the differential trend.

The table indicates Brady clearly became a better quarterback as his career progressed. His Passing Net Expected Points numbers look very good on the surface, and he has six seasons in which he finished in the top five in Passing NEP, including three seasons where he was the number-one quarterback overall.

By no surprise, he's been good and quite consistent during his career. But is his regular season success enough to qualify him as the greatest? Just being consistent doesn't mean a quarterback is fit for the lofty title of the best, after all. Let's look a little closer.

To paint a fair picture of how Brady's overall numbers stack up, it's important to keep league-wide context. For this, I created a threshold of what constitutes a top-five season in terms of Passing NEP since 2000 and found that the average top-five season requires a quarterbacks' Passing NEP to be at or above 138.30. We've seen 12 different quarterbacks hit the high mark of 138.30 a total of 32 times since 2000. Using these 12 quarterbacks as a jumping board, I complied each quarterbacks' career average Passing NEP per drop back, which you can see below.

Peyton Manning has been the gold standard of quarterback performance over the years, and Brady's career accolades, while they are still very good, don't hold up against Manning, Aaron Rodgers, and Philip Rivers.

Instead, Brady is in a tier just below the best quarterbacks since 2000 in a very formidable group with Drew Brees and Tony Romo. That's certainly not bad thing to be in a grouping with those quarterbacks, but it's incredibly tough to call someone the best of all time at his position when he's not even better than the other players in his era. At least in the regular season.

But, as noted earlier on, Brady's best seasons were later in his career and came post-2007. He has to be on par with Manning and Rodgers, and above Brees and Romo now, right? Dropping Brady's less formidable years in the league from 2001-to-2006 in favor of his best seasons resulted in his Passing NEP per drop back to be 0.26, still below Peyton Manning's career mark and just above Aaron Rodgers' 0.25.

Even when cherry-picking Brady's best years, he still isn't the undisputed best of his era in regular season terms. He does jump up a tier in terms of Passing NEP per drop back, but he just isn't a cut above everyone else like Manning has been.

Of course, quarterback greatness isn't just defined in the regular season.

Playoff Performance

Of course -- and this goes without saying -- playoff performance matters when analyzing overall greatness. So, for a solid understanding of Brady’s playoff statistics, let's take a look at his per-game averages and see how they stack up among playoff quarterbacks.

The table below shows where Brady lands among the 30 quarterbacks who have attempted at least 275 passes in their playoff careers since 1970. Overall rankings are in parenthesis.

Brady's playoff numbers are very good, but even diehard Patriot fans would admit that they aren't earth-shattering.

For what it's worth, Brady has played in more playoff games than any quarterback in NFL history. That's a testament to how good the Patriots have been over the last 15 years. And Brady has certainly been successful in the postseason from a numbers perspective.

He just hasn't been the best.

To show Brady's lack of postseason superiority among the all time great quarterbacks, below are the 11 signal-callers who have started at least 10 playoff games and have compiled a quarterback rating of 85 or better since 1970. The data is sorted by descending quarterback rating.

Again, just like Brady's regular season numbers, his playoff numbers are very good. But with a little more context, they just aren't the best of all time. He doesn't lead any of these major statistical categories and actually lands sixth best -- right in the middle of the bunch -- in quarterback rating, completion percentage, touchdowns and interceptions per game. The only category Brady lands in the top five is yards per game, but he's only averaged 6.77 yards per attempt, which is last among these 11 quarterbacks.

What separates the greatest at their position is superior production among the best, something Brady simply hasn't done in the regular or postseason. He's been very good, which I keep saying, but he hasn't been the best. At least Brady's postseason production distinctly outmatches Peyton Manning here.

The only statistic Brady leads the above playoff quarterbacks in is game-winning drives, which is an impressive feat. But, like I noted earlier on, he's played in more playoff games than anyone ever. Game-winning drives is a nice stat to throw around, but it often times comes down to sheer opportunity.

The End of the Debate

So, can Brady be considered the best of all time? Not necessarily. Look, if you view a quarterback's greatness in terms of Super Bowl wins and subscribe to the notion of overall quarterback wins, then Brady is probably your guy.

But looking at regular season analytics, Brady hasn't even been the undisputed best quarterback of his era. And from a playoff perspective, there are other quarterbacks who have been more impressive.

Perhaps when you combine the two -- regular season and postseason numbers -- you get one of the greatest quarterback of all time. And Brady definitely deserves to be in the conversation. But from a statistical perspective, it's tough to crown him, hands down, as the best quarterback ever.