The Two Point Conversion When Eight Down

[pete fabrizio]

Greensboro 15, Guilford 14
http://www.d3football.com/story.php?story=5351

"Down 14-6, Pride coach Marion Kirby surprised many in the crowd of 2,211 when he decided to forgo the traditional extra point and go for the two-point conversion.

"We went for two so we had a chance to win [if we scored another touchdown]," said Kirby. "We wanted to kick to win at 15-14. That's nothing new that I've done. We go for two then, if we make it, we kick to win it. If we not, we are going to go for two the next time to try to get it into overtime. It's just as simple as that.""

His explanation should sound fine to a non-mathematical fan -- I can just imagine hearing Al Michaels explaining it.

[David Sklansky]

Great. Now let's start talking about the larger point.

[The Dude]

The frequency that NFL coaches make awful decisions is embarrassing. They kick field goals when they should go for a TD/ first down, they punt when they should go for it, they kick the extra point when they should go for two... and they do it every week.

I had never noticed the situation you just pointed out, but yes, it's very clear. Going for two will win the game 5.32% more often (of the times when you score twice), given your numbers - and I'm almost certain the 2pt conversion rate is higher than that the past two years.

If you have a rational explanation for why every coach makes these errors, I'd like to know. Is it possible that nobody with access to NFL coaches/owners has ever done these calcs? Do you think coaches and owners aren't smart enough to understand it? I've heard the "coaches are afraid to make these unorthodox decisions and have them backfire, because they want to keep their job" argument, and I'm not convinced.

[wheatrich]

expected value for each instance (assuming all stats given are correct) [also assuming team only has time to score twice]
Two point conversion
.42*2+.58*0=.84
One point conversion
.98*1+.02*0=.98
By kicking the extra point you gain .14 points.
However, that's not the situation we're in.

down 14 go for 2
win .42 of time then .98 kick xp for win= .42*.98=.4116
lose .58 of time then win .42 to tie=.58*.42=.2436
(everything else is a loss)
exp value for that team then to win
.2436*.5=.1218
so win percentage is .1218+.4116=.5334

kick both to tie .98*.98=.9604
expected win
.9604*.5=.4802

Thus, it appears that by going for 2 you gain about 5% in win equity.

Even that being done; I believe there is a psychological value lost when a team is down 8 instead of 7 since they're now thinking "now we've got to do two things instead of one to tie the game". Also, I believe that (wish I had stats to either confirm or discredit this) the team blowing that lead is more likely to lose the game than the team with the momentum. If that combined is just a 6% net swing then obviously kicking is correct.

[kdotsky]

They always choose the "passive" play (e.g. not going for the two points). This type of mistake is hardly noticed (punting doesn't make a good highlight). "Going for it", on the other hand, is exciting and makes it to the highlight real -- so if it backfires it gets a lot of attention.

So coaches make the mistakes that don't get attention, and then can blame the game on whatever didn't go great, e.g. turnovers. In a way, they may be maximizing their own $EV. A highlight-real backfire loses them a lot more (in terms of long term compensation) than a mistake nobody notices.

[wheatrich]

[ QUOTE ]
they kick the extra point when they should go for two


[/ QUOTE ]

Often this is also the other way around. Some coaches know but realize the heat they would stand if it didn't work. Most just aren't smart enough to know any better. It's that way in every major sport. It's the classic battle of the traditional view vs the educated view of how things should go. The analysts with the most TV air time are the previous version so that's why that's still currently prevailing despite how many times it's been proven that they are incorrect.

[joes28]

Id like to see a stat about how many times a team converts a two point conversion on their second attempt in the same game.

Most teams only have a few plays that they plan on running in a 2pt situation, though i guess if they were always following this strategy they would practice it more often, but im guessing that the more 2pt plays u run in a game the lower the success rate becomes.

[The Dude]

[ QUOTE ]

So coaches make the mistakes that don't get attention, and then can blame the game on whatever didn't go great, e.g. turnovers. In a way, they may be maximizing their own $EV. A highlight-real backfire loses them a lot more (in terms of long term compensation) than a mistake nobody notices.

[/ QUOTE ]
I don't buy that every coach in the league actively makes decisions that he knows gives his team a smaller likelihood of winning, simply because he is afraid of a highlight reel. Some coaches might, but several NFL coaches strike me as the type who aren't afraid of taking risks and failing.

[PairTheBoard]

[ QUOTE ]
They always choose the "passive" play (e.g. not going for the two points). This type of mistake is hardly noticed (punting doesn't make a good highlight). "Going for it", on the other hand, is exciting and makes it to the highlight real -- so if it backfires it gets a lot of attention.

So coaches make the mistakes that don't get attention, and then can blame the game on whatever didn't go great, e.g. turnovers. In a way, they may be maximizing their own $EV. A highlight-real backfire loses them a lot more (in terms of long term compensation) than a mistake nobody notices.

[/ QUOTE ]

In this particular case, the problem for the image concious coach is that he will look bad a large part of the time. More than half the time they will miss the two pointer. And then they will usually not score again. Instead of a simple loss caused by not scoring again after a normal 1 point conversion, people will talk about the unconventional decision to go for the missed Two. Going for Two only makes the coach look good when they make it, 42% of the time, and then score again which is unlikely. It makes him look bad at least 58% of the time when they likely don't score again.

PairTheBoard

[kdotsky]

[ QUOTE ]
[ QUOTE ]

So coaches make the mistakes that don't get attention, and then can blame the game on whatever didn't go great, e.g. turnovers. In a way, they may be maximizing their own $EV. A highlight-real backfire loses them a lot more (in terms of long term compensation) than a mistake nobody notices.

[/ QUOTE ]
I don't buy that every coach in the league actively makes decisions that he knows gives his team a smaller likelihood of winning, simply because he is afraid of a highlight reel. Some coaches might, but several NFL coaches strike me as the type who aren't afraid of taking risks and failing.

[/ QUOTE ]

I agree they wouldn't actively decide something like this. Though I do think the idea has some effect on them, maybe subconsciously.