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Comment by Zimahl | Hacker News Reader

Why would you ever go for it on 4th and 1 inside your own 10 yard line? You would put yourself at a severe disadvantage if you failed.

Since the data from this is from previous plays in the last 10 or so seasons it is flawed. There probably isn't very little data of a team going for 4th and 1 and that deep in their own territory. The only time this has probably happened is in extraordinary circumstances - specifically in a game-winning drive scenario with time expiring, where the defense is in 'prevent'. In these cases it is highly successful in that situation but you don't have the time to get the score.

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I think statistically, if you punt from the 9 yard line, the other team is going to get excellent field position (around the 50 yard line). The difference between failing on 4th and 1 from your own 9 and the other team getting the ball around the 50 yard line is 41 yards of field position.

That may sound like a lot, but I'd imagine the actual point difference is on the order of 2 points.

The more interesting thing to consider would be whether taking a safety there is ever a positive.

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/espn/wire?id=1653659

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.

Exactly. Punt from the 1 and the Broncos will have the opportunity to burn clock and still likely kick a field goal, forcing you into a touchdown-required situation. As it was, the free kick netted even more yards than expected.

Going for it on 4th and 2 in the '09 game was the right decision, and few knowledgeable commentators disparaged Belichick for it. Manning was dissecting the Pats defense at that point in the game: He had a much greater chance of scoring a touchdown than the Colts defense had of stopping the conversion.

Now the playcall...

If you turn the ball over before reaching your own 30, you give the other team at least 3 points, because a field goal at that distance is trivial.

This bot also requires both coaches to follow it's recommendations, because otherwise the comparison between what they call "point values" of the two teams becomes meaningless.

I was thinking the same thing about 4th&short in your own red zone - generally the data points you'll get are from desperate late-game plays where the defence is also not playing to their standard playbook.

In place of 4th and 1 data AdvancedNFlStats would substitute 3rd and 1 stats. And I would agree that this substitution is suspect. Just a bit shy of bogus in fact.

Well, getting a yard in the NFL isn't typically a big problem and 3rd and 1 vs 4th and 1 are feasibly no different. But turning the ball over inside 30 yards is at least 3 points for the other team with only rare exceptions.

I think the biggest difference is that on 3rd and 1, the defense has already assumed that they're going to get a 1st down. The main job of the defense is to prevent a big gain and then get ready for stopping the offense on the next four downs. I wouldn't say that they're cheesedicking it, but they're not going all out.

Meanwhile, on fourth down, the defense is amped up and ready to roll. You'll usually see a strong blitz against a sputtering offense, and the percentage of plays that actually get a yard is going to be lower.

Not only that, going three-and-out means that the offense is unlikely to do any better going from the 10 to the 20 yard line. Better to punt the ball, trust your defense, and have your offensive coordinator fix whatever is going wrong.

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