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How Coaches and the NYT 4th Down Bot Compare

nytimes.com

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Re: How Coaches and the NYT 4th Down Bot Compare

#31

Post by gerad »

thejteam wrote: post #7

This was discussed some in https://news.ycombinator.com/item?id=6728821 I've thought about it some since then and I'm also not convinced that expected points is a good metric. That will maximize the expected point differential per season but I am not convinced (although I could be wrong... I haven't put pencil to paper to make my thoughts rigorous) that there are enough possessions in the game on average to make this…

The best defense is keeping the other team's offense off the field. Going for it on fourth down has a much higher probability of doing that than a punt does.

Re: How Coaches and the NYT 4th Down Bot Compare

#32

Post by twoodfin »

aero142 wrote: post #28
timfrietas wrote: post #5

This does not take into account an important factor that is somewhat intangible, but real to the psychology of the game: point swings. If you go for it on 4th and 1 at your own 1 and lose you are definitely down 3 points and probably 7. This puts pressure on your offense--which just failed on a 4th and 1--to somehow make it all the way down the field next time. That can be demoralizing for that offense, paralyzing in…

This actually seems measurable. Do teams that are behind perform worse on average? Do teams perform worse than normal after failing a 4th down attempt?

The same statistics wonk has done a lot of work on "momentum" in games. His conclusion is that there is no such thing:

http://www.advancednflstats.com/2013/11/momentum-1.html

That jibes with my own anecdotal experience watching a lot of football, despite how often announcers like to cite it as a factor.

Re: How Coaches and the NYT 4th Down Bot Compare

#33

Post by swang »

twoodfin wrote: post #29
swang wrote: post #24

Earlier quoted context omitted.

No. Because you cost yourself 2 points and you give the ball to them. Essentially you gave them 2 points at the cost of being able to "punt" the ball at the 35.

Ah, but sometimes two points is not so bad if the clock is a factor and you're about to turn over possession regardless. Down by one and facing a fourth down against the Broncos from his own one yard line with three minutes to go, Bill Belichick famously took an intentional safety[1]. The field position gain from the free kick was worth the two points, and the Patriots went on to win. [1] http://sports.espn.go.com/es…

Ah interesting, I have never heard about this game specifically.

It seems though he gave up some amount of EV by giving up the 2 points to the Broncos, thus a FG later on would only tie the game instead of winning it. But I assumed this was offset by the risk of having to punt and the Broncos end up getting a FG where then they'd be up by 4 points.

I don't know if Belichick was right to do this, but it paid off for him which is why everyone pats him on the back.

Contrast this with the 2009 Colts/Pats game where he went for it on 4th and 2 on his own 28 and didn't make it.

Re: How Coaches and the NYT 4th Down Bot Compare

#35

Post by dfan »

It is interesting what an emotional reaction people instinctively have to 4th down. Going for it on 4th down and failing feels like a catastrophe. But punting would have given the ball away anyway, so all you've done is give the opponent an extra 40 yards or so. Which is bad, sure, but it's a hell of a lot less bad than, say, throwing an interception on 1st and 10. But somehow giving up the ball on downs has come to be seen as a massive failure, on par with an regular turnover.

Re: How Coaches and the NYT 4th Down Bot Compare

#36

Post by foobarqux »

gerad wrote: post #30
slg wrote: post #12

These type of articles never take into consideration the reason why coaches don't go for it as often as a computer might. The coaches face a reverse moral hazard when taking risks because the negative outcomes are multiplied for them. Even if the statistics support their decisions, a coach will be fired for taking too many risks and failing. Is gaining an extra 2% (or whatever) in expected returns worth the risk of l…

I think there's selection bias in the underlying data. The dependent variable (realized success on attempted 4th down conversions) is conditioned on 4th down attempts by coaches. Since coaches are conservative, they're likely to go for fourth down conversions only in cases when they are likely to succeed (due to defensive mismatches, etc). Hence the model may over-estimate the benefit of going for it on fourth down.

Moreoever, the probabilities are likely to change if behavior changes. For example fakes or trick plays become less successful if you do them often.

Re: How Coaches and the NYT 4th Down Bot Compare

#37

Post by Uhhrrr »

zeroonetwothree wrote: post #22
Uhhrrr wrote: post #2

Hm, so the data points for likelihood of getting another first down is based on data from the fourth downs that coaches actually attempted? It may be that the fourth downs they didn't attempt were not as propitious for some reason - wind (which the authors mention), injuries on key players, lateral positioning which doesn't favor one formation or another, etc.

No, it's based on third down data. The likelihood of converting 3rd and 1 is probably similar to that of converting 4th and 1.

Thanks! I read poorly the first time.

Re: How Coaches and the NYT 4th Down Bot Compare

#38

Post by javanix »

spinlock wrote: post #25
symbaton wrote: post #13

Earlier quoted context omitted.

People always say this, but it is actually true? Has any coach ever been fired for missing too many fourth downs?

Ask Nick Saban how trying to kick a field goal with 1 second left in the Baylor game is working out for him. There are plenty of people saying that any other coach would be fired.

That particular outcome had happened less than 5 other times in the history of the modern NCAA. 99/100 times that game ends with either an Alabama win or O.T.

He hardly made a controversial decision.

Re: How Coaches and the NYT 4th Down Bot Compare

#39

Post by snowwrestler »

The fundamental flaw with this analysis is that statistics are descriptive, not predictive.

You can't reliably predict the future with statistics alone. If you could, then technical analysis of the stock market would be the most successful investing strategy. It is not.

Likewise, a lot of folks seem to think that taking an historical statistical trend and extending it into the future is a scientific approach to football coaching. It's not.

Scientists use statistics to understand evidence, but they formulate theories in terms of root causes. In other words it's not enough to know that dropping a hammer has a high correlation with acceleration of 10 meters per second squared. If you want to predict how fast other objects in the future will fall, you need a theory that describes why and how anything falls.

It doesn't look to me like the 4th down bot embodies or implements any cohesive theory of football success. It just finds trends and dots the line into the future.

Re: How Coaches and the NYT 4th Down Bot Compare

#40

Post by snowwrestler »

dfan wrote: post #35

It is interesting what an emotional reaction people instinctively have to 4th down. Going for it on 4th down and failing feels like a catastrophe. But punting would have given the ball away anyway, so all you've done is give the opponent an extra 40 yards or so. Which is bad, sure, but it's a hell of a lot less bad than, say, throwing an interception on 1st and 10. But somehow giving up the ball on downs has come to…

Turning it over on downs is a turnover, as sure as fumbling is. It's not accounted that way in the box score, but in terms of impact on the game it is the same.

An interception is better or worse than turning it over on downs by the field position delta. If it is returned past the line of scrimmage, then it's worse. If it is not returned, it's better. A deep interception with no return is like a punt in terms of impact on the game.

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