Off the top of your head, could you say exactly how the NFL passer rating is calculated?
Probably not. I'm sure you could look it up quickly, but it doesn't matter that much anyway. Because as long as we understand what goes into the rating, the exact formula isn't that important. The passer rating aggregates yards per attempt and completion percentage as well as TD and INT percentages into one more-or-less easy to understand number.
For all its faults, the passer rating does go beyond simple volume stats like yards, number of TDs or number of interceptions. This is a good thing. Yet to this day, it remains perhaps the only advanced stat used to evaluate a passer. That is not such a good thing.
So today I'm going to look at some stats out there that help paint a more complete picture of the passer performance than the passer rating or the more traditional volume stats are able to, and I'll use the four NFC East quarterbacks as an example.
Just so we can get it out of the way, let's start with where the four NFC East QBs currently stand as measured by the traditional Passer Rating:
|2016 Passer Rating, NFC East QBs|
Dak Prescott and Kirk Cousins are fairly close together at the top of the passer rating rankings and are two of the most effective passers (as measured by passer rating) in the league this year.
The NFL average passer rating so far this year is 89.5, which makes Eli Manning an average passer, which is perfectly in line with his career average over 13 seasons: just a shade below average. Carson Wentz at this point is playing like a slightly below average quarterback, but at least he has the upside of youth.
You may have noticed that I used the word 'passer' 14 times above, while I used 'quarterback' just twice. This is an important distinction. The NFL passer rating was designed to evaluate the passing game only. It does not account for a quarterback's running game, his ability to read defenses, his competence as a signal-caller, his decision making and many other aspects of quarterback play.
ESPN's QBR is an attempt to fix some of the weaknesses of the traditional passer rating. ESPN's Sharon Katz and Brian Burke (formerly of Advanced NFL Stats) explain the concept:
Traditional box score stats distort the performances [...] because they (1) fail to account for all of the ways a quarterback can affect a game, (2) don’t put plays into the proper context (a 5-yard gain on second-and-5 is very different from a 5-yard gain on third-and-10), and 3) don’t acknowledge that a quarterback has teammates who affect each play and should also get credit for everything that happens on the field.
ESPN's Total QBR includes a lot more than the traditional boxscore stats, and instead tries to include all of a quarterback’s contributions to winning, including how he impacts the game on passes, rushes, turnovers and penalties. Total QBR, much like the Expected Points concept, looks at every single play, adds context (e.g. down-and-distance, score differential, win probability etc.) and then allocates credit to the quarterback and his teammates to produce a clearer measure of quarterback efficiency.
Here's what the Total QBR for all four QBs looks so far this year.
|2016 Total QBR, NFC East QBs|
|2016 Total QBR||86.2||74.5||58.7||45.5|
There is are some minor differences in these rankings compared the the passer rating rankings. Prescott moves up a few spots, Wentz moves down a few spots, Cousins and Manning rank roughly where they ranked in passer rating. So let's move on to the next stat.
Defense-adjusted Value Over Average is a proprietary metric developed by Football Outsiders which adjusts performance for down and distance situations and also adjusts for opponent strength. Football Outsiders explain:
Conventional NFL statistics value plays based solely on their net yardage. The NFL determines the best players by adding up all their yards no matter what situations they came in or how many plays it took to get them. Now, why would they do that? Football has one objective -- to get to the end zone -- and two ways to achieve that -- by gaining yards and achieving first downs. These two goals need to be balanced to determine a player’s value or a team’s performance. All the yards in the world won’t help a team win if they all come in six-yard chunks on third-and-10.
Doing a better job of distributing credit for scoring points and winning games is the goal of DVOA, or Defense-adjusted Value Over Average. DVOA breaks down every single play of the NFL season, assigning each play a value based on both total yards and yards towards a first down. [...] Every single play run in the NFL gets a "success value" based on this system, and then that number gets compared to the average success values of plays in similar situations for all players, adjusted for a number of variables. These include down and distance, field location, time remaining in game, and the team’s lead or deficit in the game score.
Here's how the four NFC East QBs grade out according to DVOA (note that the data is only through week 11, as FO hadn't updated their data by the time of this writing).
|2016 DVOA, NFC East QBs|
Again, the picture remains fairly similar: Prescott and Cousins at the top of the heap, Manning and Wentz somewhere around average or a little below.
Deep passing accuracy
One of the most persistently misrepresented aspects of Dak Prescott's game is his alleged lack of accuracy on deep balls. But he stacks up fairly well against the other NFC East QBs. The next table shows each QBs deep passing accuracy, which measures the accuracy on passes that travel 20 yards downfield through the air. For good measure, the passer rating on those passes is included
|2016 Deep Passing Accuracy, NFC East QBs|
|2016 Deep passing accuracy
||31% (12-39)||29% (10-35)|
|Deep ball passer rating
None of the QBs assembled here can measure up to the 2016 God Emperor of the Deep Ball though. Matt Ryan has completed 20-of-42 deep ball attempts for 826 yards and seven TDs, good for a 133.4 passer rating.
Of the four NFC East QBs, Cousins throws deep the most often and is the most accurate while doing it. Prescott has the fewest attempts of the four, but has the second-best completion percentage of the group.
Passing under pressure
We all have our pet theories about NFL QBs, about how one guy is particularly efficient, how another guy throws a great deep pass, or how yet another is particularly good under pressure.
Well, we already saw that for the first two points, we have some surprising results even among the small sample of the four NFC East QBs. The latter point, passing under pressure, is yet another one where the data defies some of the established storylines.
|2016 Situational Passer Rating, NFC East QBs|
Prescott, Cousins and Wentz play about as well when they are blitzed as they do when they aren't. Manning appears to be particularly susceptible to pressure, as his passer rating drops by over 20 points when pressured.
Texas lore holds that the legendary UT football coach Darrell Royal once said, "Three things can happen when you pass the football, and two of them are bad."
Obviously, there is no single stat that measures a QB's decision making. But interceptions (even if they are partly driven by bad luck) can be a proxy for bad decisions.
|2016 Interception rate, NFC East QBs|
In today's pass-heavy NFL, the passer who can pass effectively while minimizing his mistakes is going to be the more successful player. In the NFC East this year, that player is Dak Prescott. He has the fewest interceptions per pass attempt, remains the most effective under pressure and is right up there in terms of accuracy and deep ball passing skills.
Having said all that, it shouldn't come as a surprise to see that Dak Prescott leads the team with the best record in the NFC East.