Tuesday, July 6, 2010

The QB - The Evolution of the Passers

As mentioned in this earlier post, one thing I wanted to look at was how much quarterback play has improved recently. I decided to take a look at the last several decades, because what I wasn’t sure of was whether recent play has spiked – i.e. QBs are improving at an accelerated rate – or if it’s just part of an overall trend.

It's worth calling out that this is probably as much of a statement about how much passing offenses have evolved over the last few decades as it is telling how much the QB has evolved. The rules of the game have changed over the years, and a couple of key innovations have happened which opened up passing offenses. Those deserve to be discussed a bit before getting into the statistics of the players themselves.

The Rules of the Game Have Changed

Much as I dislike the Steelers, there’s a great site set up by Steeler fans that lays out some (all?) of the major rule changes and when they occurred. A summary of the evolution of the rules governing the passing game:

Between 1974 and 1978, the NFL adopted rules to dramatically open up the pass. Prior to ’74, it was virtually anything goes against WRs. The physical corners like Night Train Lane and Dick LeBeau ruled the roost, able to knock receivers off their route with near impunity. In 1974, the NFL began restricting the contact DBs could have with receivers down the field. In 1977, defenders were limited to only contacting the receiver once down the field.

And in 1978, we got the big rule change that ushered in what many people refer to as the modern era of the passing game. The new rule established that defenders could not come in contact with receivers beyond five yards past the line of scrimmage. This opened up the long passing game, and over the next ten years, the QBs in this data segment threw 15% more passes per game than they had in the nearly 2 decades back to 1960. And that’s just QBs with over 200 attempts. Attempts per QB per game have continued to increase ever since, although not at the same rate.

Note the shift in the trend line (6-order polynomial) between ’78 and ’88. Two interesting outliers bear mentioning. I started by looking at total attempts, but 1982 stood out as a massive outlier, which I realized was due to the strike-shortened season. I normalized this by simply adjusting to look at passes per QB per game, which also helped me strip out the bias in the NFL moving from 14 to 16 games in a season. Then, in 1987 there’s an unnatural dip in attempts per game. Removing that outlier actually adjusts the decade from a 15% increase in per game attempts to 17% per game. Between ’79 and ’88 there’s no season with less than 24 att/game except ’87, at 21.3 per game. It’s an outlier for which I can’t seem to find a cause, but clearly stands out.

The rules continued to evolve in the mid-‘90s to help the passing game flourish. In ’95, QBs gained the ability to use a microphone to receive communications from the sideline. In ’96, they re-emphasized the five yard downfield contact rule. In ’01, protection of the passer began being emphasized even more, allowing QBs to worry less about where and when they’d be hit; and in ’06, defenders were restricted from hitting passers below the knee. It’s known as the “Tom Brady rule” but in reality it was put in place more due to Carson Palmer’s knee injury in the post-season loss to the Steelers where Palmer – coming off a season where he could have been MVP if not for Peyton’s amazing year – went down very early in the game. Somewhere in the mid-‘00s as well saw an additional re-emphasis of the five yards downfield contact rule, though I can’t find exactly when that happened.

The Passing Game has Seen at Least Two Major Innovations

The first was Don Air Coryell’s (RIP) offensive innovation with the Chargers between ’78 and ’83. Leading Dan Fouts to a Hall of Fame career, Coryell emphasized an attack on every part of the field. His contributions led to two things that have redefined offensive positions in the league. One was changing the tight end position from a blocker little used as a receiver into a down-field attacker. The second was the evolution of the running back position in the creation of the H-back (for passing game purposes as a pass blocker) and using the RB as a receiver. He’s credited with evolving offenses, and forcing defensive evolution to defend his passing attack, forever changing the landscape of the league.

The second was Bill Walsh’s development of the West Coast Offense in the mid-‘80s. This emphasized short, precise passing in order to later open up defenses to allow for longer plays. Montana worked this system to near perfection, completing 64% of his passes for 7.8 YPA with 190 TDs (5.5%) to 91 INTs (2.6%) between ’83 and ’90. He went 84-24 regular and 11-5 post season in that stretch, including three Superbowl wins. It of course helps to have Jerry Rice as your side-kick through much of that.

The WCO and “Air Coryell” offenses are seen in some form across virtually the entire NFL today. Some props should be given to “Mad Mike Martz” and his crazy-effective passing offense run with the Rams (a derivation of the Air Coryell offense). But this largely didn’t really innovate or change the dynamics of the league in near the fashion of Coryell’s and Walsh’s offensive advancements.

And with this, we come to the core of how much better quarterback play has been in the last few years. I started with the hypothesis that QB play over the last decade has been improving at an accelerating rate. The data seem to support this, though not to the extent to which I thought. The below graph shows the median and maximum QB rating for the top 25 passers, by season.

This only graphs back to the mid-‘70s, when 25 QBs qualified. Once again, I added a 6-order polynomial trend line for the median QB rating to show how it’s trended over the years. You can see the increase trending in the late ‘70s and early ‘80s. The trend then flattens from the mid-‘80s to the mid-to-late-‘90s, increasing just a little bit. In the late ‘90s, the increase begins to accelerate again, with a recent somewhat sharp increase in the rate of improvement.

The early increase tracks nicely with the five yard contact rule change, and the Walsh/Coryell innovations. The more recent one, however, does not. In the past five years, median QB rating has increased about 5% faster than median QB rating over a five year stretch a decade ago. But where we see real change is in the extremes. The first graph below shows the number of QBs with a > 100 and > 90 QB rating by season. The second graph shows the number with a < 80 QB rating by season (remember, only taking the top 25 QBs by season).

Once again, 6-order polynomial trend lines were drawn to show emerging trends of QBs with higher than 90 and lower than 80 ratings.

The decline of QBs rated under 80 has been fairly steady since 1975. But it’s also been a sharp decline. Given the trending of this data, it’s possible that 10-15 years from now the NFL will see 25 passers with over 200 attempts that have a greater than 80 QB rating.

On the flip side, there’s been a sharp increase recently in the number of QBs with a greater than 90 QB rating. I left pre-’76 in this graph more for illustrative purposes, to show that there were QBs that were capable of throwing 200+ times for some very impressive ratings. But over the last decade, a significant increase in the number of QBs with > 90 QB rating has been seen. The past ten years have seen 85% more QBs with a 90+ QB rating than the previous ten years. While QBs with a 100+ QB rating have increased in that time, there aren’t enough instances to truly see how this is trending.

In conclusion, QB play has almost certainly improved a fair amount over the past several years, including an impressive improvement over the last few years. Almost certainly some portion of this is due to improved passing offense overall…better receivers, better offenses, more favorable rules. But I also think the passers themselves have gotten better at the game in that time.

What that means is we are not able to look at “overall” numbers to come to any sort of conclusion as to who the best is, or even how good a player is. This leads to the McNabb discussion. McNabb will almost certainly finish his career in the top ten in completions, attempts, passing yards and TDs; and in an amazing achievement, will likely not crack the top 50 in INTs thrown. But we can’t evaluate him based on his overall numbers, given how much QB play and passing offenses are improving. We will need to look at where he stands vs. other QBs in his tenure, and compare him to where the HoF QBs stood vs. QBs in their own time.

Thus laying the foundation for the third post of the series, which I will get into tomorrow. In the mean-time, feel free to provide any thoughts or feedback on this below.


  1. If you ignore the rushing part of McNabb's career, the analysis is incomplete. Unless you think thousands and thousands of yards of rushing and first downs and dozens and dozens of TDs shouldn't count.

  2. Don't worry, I didn't, which you'll find out in a few minutes.

  3. Remember the strike of 1987? Week 3 was cancelled, and weeks 4-5-6 were played with replacement players.

    It makes sense for there to be a dip in passing attempts that year, as coaches simplify their game plans with replacement players. There's a semi-famous incident where the replacement Niners played a game against the Giants, and Bill Walsh had his offense line up in one of the really old-school formations, like a Wing-T or something. Parcells does a double-take on the sideline, then busts out laughing.

    So there's the father of the West Coast Offense using primarily a running attack during 4 games of the season. That all by itself would move the needle on passing attempts per game, downward. Never mind what all the other coaches were doing.


About This Blog

Twitter: oblong_spheroid

  © Blogger templates The Professional Template by Ourblogtemplates.com 2008

Back to TOP