Comments on Advanced NFL Stats: Who 'Dat Gonna Kick Onside to Start the Second Hal...

Correct.

2010-02-09T20:49:15.105-05:00

Correct.

So if I wanted to calculate expected points added ...

2010-02-09T18:56:25.734-05:00

So if I wanted to calculate expected points added for a game or season, I should use the values contained in the spreadsheet, corret?

Jay-One shows the EP value of going for it from th...

2010-02-09T14:24:31.046-05:00

Jay-One shows the EP value of going for it from the 1 yl. The other shows the EP value of what coaches tend to do (kick the FG).

Hi Brian, Quick question regarding EP values on 4...

2010-02-09T14:09:48.381-05:00

Hi Brian,

Quick question regarding EP values on 4th down. In your 12/16 post on expected values, with the values shown in a spreadsheet, it says expected points on 4th down on the 1 yard line is only 2.29. Yet in the image that you have attached in the above comment shows much higher values on 4th down.

I'm just wondering if you have updated 4th down values based on yards to go or if there is an equation we can use to estimate 4th down values based on 3rd down values?

Thanks Brian

This may shed some light. It's a league-wide baseline, but it's pretty clear punting was a bad option.

The argument is really between going for it and kicking the FG. In Baltimore, Stover would only be asked to kick from that distance in desperation. He must have believed he had a 50/50 shot or a veteran like him wouldn't have gone out there. The NFL average is 60% from 51 yards out, but that includes all types of conditions. Winds were very light last night in Miami--4 mph, and the footing was solid. So kicking the FG was a defensible decision.

On the other hand, when there are two very strong offenses out there, POSSESSION IS EVERYTHING. This makes the go-for-it option much more lucrative. The league average on 4th and 11 is about 30%, but with Manning, Wayne, Clark, etc, it's certainly a little higher.

In the final analysis, assuming Stover is 50/50 from 51 yards, the break-even success rate required to make the 4th down attempt worthwhile would need to be 75%.

The WP model agrees . It shows that the conversion attempt would be a -0.02 WPA mistake.

The Colts were literally in a no-win situation. The problem was that it was 4th and 11. That screen to Collie on the previous play lost 3 yards. And the 1st down run by Addai only gained 2. Had it been a closer to 4th and 7, I'd say go for it.

Whoops looks like Anonymous stole my thunder...

2010-02-08T22:16:46.739-05:00

Whoops looks like Anonymous stole my thunder...

What about the 51 yard field goal attempt? Any wa...

2010-02-08T22:16:14.762-05:00

What about the 51 yard field goal attempt? Any way to estimate Stover's chances of making it? There was a lot of second guessing on that one even though it was a 4th and 11...

Brian, are you going to do an analysis on the 51 y...

2010-02-08T17:10:07.425-05:00

Brian, are you going to do an analysis on the 51 yard FG the Colts attempted? I don't think that is a high percentage play with Matt Stover.

I meant botched snaps on kick attempts. They often...

2010-02-08T15:57:27.095-05:00

I meant botched snaps on kick attempts. They often appear in the stats as 2-pt attempts because the holder may try to run or throw after an aborted kick. The Romo bobble vs. Seattle is a good example.

It would be interesting to break down the 2-pt dat...

2010-02-08T15:57:10.641-05:00

It would be interesting to break down the 2-pt data. Take all the teams and put them into four buckets: 1) good offense, 2) bad offense, 3) good defense and 4) bad defense. Define good as the top 1/3rd in the league and bad as the bottom 1/3rd. Use hindsight to determine good and bad by using the entire season's rankings. This would give you four categories of matchups, for example good offense vs bad defense. You would be left with four percentages for 2-pt convertibility. This procedure can be done with the last 10 years worth of data. Hopefully you can get 100+ population in each sample. This analysis could be taken further to make the results more robust.

I was thinking of exactly what Kulko said. In an...

2010-02-08T15:56:03.896-05:00

I was thinking of exactly what Kulko said.

In any case, I think the better direction to approach it is to start with the break-even success rate. In other words, what success rate would make the 2-point attempt (or onside kick, or 4th down attempt) worth it? Then the coach can estimate what he believes his own team's chances are, and whether it exceeds the break-even.

The league-wide baseline success rate is still helpful in calibrating the coach's own estimate of his team's chances. He can take the baseline and bump it up or down depending on situational considerations, such as the relative strength of the lines, weather, or whatever else might come into play.

Too often I hear coaches and analysts start with the mitigating considerations without knowing the baseline. Essentially they are just seeking a rationalization for an intuitive decision. We all do that everyday.

I think real coaches are more likely to accept that 'break-even' analysis instead of just saying 'my computer says go for it.' They stay in the decision process and it basically just informs them without replacing their judgment.

Shouldn't botched snaps be counted towards the...

2010-02-08T15:49:24.314-05:00

Shouldn't botched snaps be counted towards the 1-pt attempt conversion rate? Are they so rare that they do not significantly affect the 99% success rate?
I could imagine that a small number of botched snaps could affect the 2-pt rate significantly without affecting the 1-pt rate because there are so many more 1-pt tries. What do the numbers say?

The OFF and DEF facing each other in each specific...

2010-02-08T15:02:46.684-05:00

The OFF and DEF facing each other in each specific Attempt have varying level of skill. that could shift the true mean of any attempt like 20% in one direction or the other.

I'm not a football expert, I know very very li...

2010-02-08T14:04:36.730-05:00

I'm not a football expert, I know very very little actually. In which ways are each 2-point conversion unique?

It's a little more complicated than a standard...

2010-02-08T12:19:30.043-05:00

It's a little more complicated than a standard t-test measuring sample error. It's not like a weighted coin that's always 45% or 50% or whatever. Every 2-pt conversion is unique, so you have some situations that are 55%, some that are 40%, some that are 50%. Any individual season might feature more or fewer of each type of situation. So there are 2 random functions working on top of each other, and the variance is going to be wider than a standard statistical test would tell us.

Agree that the Colts erred by not running on 3rd a...

2010-02-08T11:59:56.541-05:00

Agree that the Colts erred by not running on 3rd and long.

Brian, can you analyze the Colts FG attempt from 5...

2010-02-08T11:24:17.899-05:00

Brian, can you analyze the Colts FG attempt from 51 yards? It was a tough spot. Third and long from the area where a punt does no good. I bet generally a FG attempt would be the right call, but Stover is bad from long distances. I think the real mistake was on third down. If they had contemplated using all 4 downs they could have run a short play on third to set up a conversion or a shorter field goal.

Payton is quoted as saying he felt they had a 60 t...

2010-02-08T10:47:45.176-05:00

Payton is quoted as saying he felt they had a 60 to 70% chance to recover the onside kick. That sounds familiar...

Using a 95% confidence interval (CI) and assuming ...

2010-02-08T10:43:45.692-05:00

Using a 95% confidence interval (CI) and assuming 53 attempts the range of possible real mean values for success in the conversion is between 32% and 58%.

If there were 250 attempts in the sample the 95% CI would be 39% to 51%.

"teams should occasionally attempt surprise o...

2010-02-08T10:06:01.059-05:00

"teams should occasionally attempt surprise onside kicks if they believe their chances of recovery exceed 42%"

The great part about the Super Bowl is that we actually get to hear exactly what they thought: Payton said he believed it had 60-70 percent chance of working.

Brian - just on the technical side of things to ad...

2010-02-08T09:06:35.820-05:00

Brian - just on the technical side of things to add to your point about the small sample size (and also to make sure I'm remembering my statistics lessons from school), it's a bit of central limit theorem followed by a Z-test that one would use to show that a 45% conversion rate on 53 attempts is well within the acceptable limits of a true probability of 0.50, right?

Also, I know this is a bit off topic. But was I t...

2010-02-08T01:44:29.779-05:00

Also, I know this is a bit off topic. But was I the only one hoping for OT? I think it is going to take an Super Bowl OT fiasco to change the rule. At the very least, the rule needs to be changed in the playoffs.

I also quoted the surprise onside kick statistic w...

2010-02-08T01:40:50.503-05:00

I also quoted the surprise onside kick statistic while watching the game, everyone seemed pretty impressed!

Right. Like you said, this season. 53 attem...

2010-02-08T01:22:10.276-05:00

Right. Like you said, this season. 53 attempts is tiny. We need a much bigger data set than that. The article even says the rate has been higher over a larger time-span.

When you consider the offensive nature of the two ...

2010-02-08T01:09:22.063-05:00

When you consider the offensive nature of the two teams the value of the onside kick probably goes up. I assume these are league averages.