Following up on our recent discussion regarding going for it on 4th down, Paul Campos writes:
The specific suggestion here is that tactics that might make sense in much lower scoring eras cease to make sense when scoring becomes higher, but neither coaches nor fans adjust to the new reality, or adjust very slowly.
This explanation doesn’t really work for the NFL, since scoring in that league has been remarkably stable for the entire post-WWII era. When we look at NFL scoring averages, it’s obvious that the game’s rules makers are constantly tweaking the rules to maintain a balance between offense and defense that results in a scoring average of about 20-23 points per game per team, with significant changes being made whenever — such as in the late 1970s when pass blocking rules were liberalized — scoring begins to fall outside this very narrow range.
I had no idea! I remember when I was a kid there was a Super Bowl that was 16-6. Before that the Dolphins beat the Redskins 14-6, and then there was that Jets-Colts Super Bowl which was a few years before my time. Nowadays it seems like the games all end up with scores like 42-37. So it had been my general impression that average points per game had approximately doubled during the past few decades.
Actually, though, yeah, at least in the regular season the scoring has been very stable, with an average of 20.5 points per team per game in 1980 to an average of 23.0 in 2021. OK, actually 23.0 is a bit higher then 20.5 (and I’m not cheating here by picking atypical years; you can follow the above link to see the numbers).
Also, I was a football fan in the mid-70s, which was a relatively low-scoring period, with about 19 points per team per game on average.
My cognitive illusion
So yes, there has been an increase in scoring during the past several decades, but not by nearly as much as I’d thought. I feel like there’s an illusion here, which has two steps:
1. A 12% increase (from 20.5 points per game to 23.0) might seem small, especially when spread out over decades, but it was actually noticeable to a casual observer.
2. I did notice the increase, but in noticing it I way overestimated it.
I wonder if my error is similar to the error that economists Gertler et al. did when overestimating the effect of early childhood intervention. As you might recall, they reported a statistically significant effect of 42% on earnings. But to be “statistical significant,” the estimate had to be at least about 40%. If you follow the general procedure of reporting statistically significant results, your estimates will be biased upward in magnitude (“type M error”).
Now consider my impressions of trends in football scoring. Whatever impression I had of these trends came from various individual games that I’d heard about: not a random sample but a small sample in any case. Given that average scores have increased in the past few decades, it makes sense that my recollections would also be of an increase—but my recollections represent a very noisy estimate. Had I remembered not much change, I wouldn’t think much about it. But the games that happened to come to mind were low-scoring games in the past and high-scoring recent games. Also, it could be that trends in Super Bowl scores are different than trends in regular-season averages. In any case, the point is that I’m more likely to notice big changes; thus, conditional on my noticing something, it makes sense that my estimate was an overestimate.
One thing that never seems to come up in these discussions is that the fans (or at least, some large subset of “the fans”) want less punting and more chances. As I wrote in my original post, as a kid, I always loved when teams would go for it on 4th down or try an onside kick or run trick plays like fake punts, double reverses, etc.
A different issue that some people brought up in comments was that the relative benefits of different offensive strategies will in general depend on what the defenses are doing. Still, I’m guessing it will pretty much always be a good idea to go for it with 4th-and-2 on the 50-yard line early in the game, and for many years this was more of an automatic punt situation.
Perhaps there’s another aspect in that concurrent trends or rule changes add to an illusion. Like more passing, more linger field goals, rules to protect qb’s, etc. Perhaps their impact is more viscerally “visible” than rule changes that could have the opposite “visual” effect – like moving the goalpoats back.
“Still, I’m guessing it will pretty much always be a good idea to go for it with 4th-and-2 on the 50-yard line early in the game, and for many years this was more of an automatic punt situation.”
That’s interesting but you’d have to take the analysis beyond the “did you make it” level to “did you score” and “did you win” to show that it’s so. There are advantages to putting other teams deep in their own territory. If you can drop a 48 yard punt from the 50, that puts a lot of pressure on the opposing special teams and offense. So the decision is contingent on special teams and the opposing offense.
These days its easy to watch a lot of games with the highlights on YouTube. It seems to me that successful teams wining by kicking field goals on 4th & short even inside the red zone, making sure to score on every trip to the red zone.
Chipmunk,
From what I’ve read, I have the impression that the analytics show that going for it with 4th-and-2 on the 50-yard line will generally improve the team’s expected point differential. But, yeah, I agree that the analysis would need to be done using real data. I’m not claiming that it’s blindingly obvious that going for it is the right decision here, just that some serious people have done the analytics and found that this is indeed the case.
Some of the rule changes have shortened the game (e.g., restarting the clock after first downs and out-of-bounds). Is it possible that points per possession have increased even though total points have not (much)? That could affect the kick/go for it trade-offs.
I think this is right. If you follow Campos’ link and look at scoring per drive, you will see that points per possession has increased about 30% just in the past 20 years. But the number of drives has also declined about 10% over that time. Unfortunately, they don’t report this data prior to 1998.
https://www.pro-football-reference.com/years/NFL/index.htm
And if you look at per play data, the story is consistent: the passing game has been revolutionized, with yards per attempt up dramatically (with no offsetting decline in yards per rushing attempt). Turnovers have also declined dramatically, and field goal kickers are much more accurate over longer distances. Basically, offensive efficiency has increased a huge amount, much more consistent with Andrew’s intuition/memory.
This also means that Campos is mostly wrong when he says this: “The specific suggestion here is that tactics that might make sense in much lower scoring eras cease to make sense when scoring becomes higher, but neither coaches nor fans adjust to the new reality, or adjust very slowly. This explanation doesn’t really work for the NFL, since scoring in that league has been remarkably stable for the entire post-WWII era.” What matters in evaluating 4th-down strategy is not points per game but offensive efficiency per play. The game has changed in important ways, and that is likely one reason that coaches have become more aggressive on 4th down. NFL teams were probably punting far too often even in the 1970s. But that became much *more* true in recent decades, as the value of a possession increased and the benefits of pinning your opponent deep in their own territory receded. The win probability gains from going for it have really increased — it’s not just in our heads.
Interesting point regarding points per possession and its relevance to Campos’s argument.
But, to get back to my misconception: I really had the impression that points per game had gone up a lot in recent decades, so when I learned that the increase was only 12%, I was surprised. Again, I think I was making two mistakes here: the first was to think that “only 12%” isn’t so much. A 12% increase is actually a lot! And my second mistake was to be using a biased method of (informal) inference, an approach to inference which would make it difficult for me to perceive a change of only 12% without massively overestimating it.
I can’t speak for you, of course, but I also would have guessed scoring was up a lot (though not 100%). And I think that is partially because a lot of offensive statistics I see (as a casual football fan), especially on the passing side, imply more scoring. There are many more 300-yard passing games now, many more games where QBs have 3, 4, or more TD passes, and many fewer interceptions. How could these awesome QBs not be scoring more points? (And in fact they are — on a per-possession basis.)
Also, media coverage focuses much more on offense today. Higher-scoring teams with great QBs get more attention, while there are few teams (like the 1970s Steelers) famed for their defense. And I don’t think that’s an illusion or bias: the SD for points scored was much larger than for points allowed last year, suggesting more variance in team offense than defense, while in the past they were more equal. The correlation with team wins was .86 for points scored last year, just -.65 for points allowed. Those changes, at least for me, suggest an increase in scoring that is larger than what actually happened.
Guy:
Interesting. Also if the variance went up then there will be more games with scores like 54-51 which will get my attention even if I’m not really following the sport.
(This is a comment I’d have left on the last post on this topic, had I read it around time of posting.) I think the idea you’re discussing in the context of football, is more broadly the Kuhnian idea of the paradigm shift, albeit as applied to a non-science. Your stage 3–“Spectators are so used to things being done that way that they don’t even question it”–is analogous to Kuhn’s “normal science” phase that precedes a shift. Experts in the field (spectators but probably also coaches, players, and others) fail to question assumptions underlying the conceptual framework, despite contrary evidence.
Applying that model, the answer to your question, Why did it take so long for us to see that we were trapped in a conceptual framework of flawed assumptions about when to use risky strategies?, is the same as the answer to, Why did it take so long for mathematicians to realize that geometry wouldn’t fall apart if parallel lines are allowed to intersect? Or for astronomers to realize that the universe need not have a center? And so forth. This isn’t to trivialize your question–I think it’s crucial, actually–but to give it context. If fields that are inherently rational and deductive, and which pride themselves on healthy skepticism, fall prey to this thinking, surely fields without those traditions are all the more likely to do so, right?