Not sure if this should be posted here since it's a different sports, but this is the "advanced stats "thread not the "advanced stats for hockey" thread and I figured some of the advanced stats people will like this:
Here's my breakdown on the math behind going for two and why it was absolutely the right call mathematically. This is from another board.
There has been a lot written about 2 point conversions being better value than extra points. So I won't go to the general theory behind that. However, I will take a look at today's specific situation and show that Shurmur was 100% right, at least mathematically. I have a friend that argues based on qualitative factors such as momentum why he was wrong. That's an argument that if it's possible to prove is beyond my pay grade. So I will just quantify the probabilities of going for 2 and not going about it the old-fashioned way.
First of all, here are my assumptions:
1) Two TDs will be scored in regulation and the Falcons will be stopped from scoring any more points. Without that, we lose regardless of what Shurmur's call was. I guess there are wacky scenarios like a TD and 3 FGs also winning, but let's not complicate things.
2) I count ties as losses as I'm sure any head coach worth his salt does. So not winning means tying or losing.
To do the math there are really only three probabilities that need to be known. Probability of a successful PAT, probability of a successful 2 pt conversion, and the probability of winning in OT.
Probability of a successful PAT and 2 pt conversion is covered in this (unfortunately slightly outdated)
FiveThirtyEight article from November 15, 2016:
According to ESPN Stats & Information Group, there have been 1,045 two-point conversion attempts since 2001,1 with teams converting 501 of those tries. That’s a 47.9 percent conversion rate; given that a successful attempt yields 2 points, that means the expected value from an average 2-point try is 0.96 points.
Interestingly, that’s almost exactly what the expected value is from an extra point these days. Since the NFL moved extra-point kicks back to the 15-yard line last season, teams have a 94.4 percent success rate, which means that an extra point has an expected value of between 0.94 and 0.95 points.
Prob of PAT: 0.944
Prob of 2pt Conversion: 0.479
For OT, I went back the last two seasons since the change to 10 minute OT. A bit of a small sample size but there have been 24 OT games and 22 of them ended with a winner. So 11/24 or ~0.458 of OT games end with a win.
Here are the following scenarios given the assumptions:
Pat Shurmur decided to go the conventional route:
That's PAT, PAT, OT.
There are two possible winning scenarios here.
Event Probability
PAT (Successful) 0.944
PAT (Successful) 0.944
Overtime (Win) 0.458333333
Prob (win) 0.408437333
Prob (win) in this scenario is calculated multiplying the probability of all of the events.
Now there's another far less likely scenario for winning. What if the first PAT is no good? The Giants still get a mulligan and can go for the 2 pt conversion to tie it and then win it in OT.
Event Probability
PAT (Unsuccessful) 0.056
2 pt Con (Successful) 0.479
Overtime (Win) 0.458333333
Prob (Win) 0.012294333
The math is done the same way. So the probability of winning with this conventional strategy is 0.408437333+0.012294333, which is about 42.07%.
Now, to do the Pat Shurmur strategy:
There are three possibilities here given the assumptions.
The 2pt conversion is good, then he goes for a PAT for the win and bipasses OT.
Event Probability
2 pt Con (Successful) 0.479
PAT (Successful) 0.944
Prob (win) 0.452176
The second scenario is the least likely one is the 2 pt conversion is good, but the PAT is missed, and then the Giants win the game in OT.
Event Probability
2 pt Con (Successful) 0.479
PAT (Unsuccessful) 0.056
Overtime (Win) 0.458333333
Prob (win) 0.012294333
The third scenario is one where the 2 pt conversion is unsuccessful, but a second 2 pt conversion is successful, and the Giants win in OT.
Event Probability
2 pt Con (Unsuccessful) 0.521
2 pt Con (Successful) 0.479
Overtime (Win) 0.458333333
Prob (win) 0.114381208
The probability of winning in this situation, if you add up all of the scenarios is ~57.9%.
Finally, a scenario dedicated to my aforementioned friend that screamed that if they were to go for 2 they should have done so after their SECOND TD, not the first. His argument was about momentum, but here I'll look at it from a mathematical perspective. I call this scenario the "reverse scenario" because it's go for 1, then go for 2, rather than the hope of going for 2 then 1.
Here there are two possible scenarios:
The ideal scenario is kicking the PAT is successful and the 2 point conversion is successful.
Event Probability
PAT (Successful) 0.944
2 pt Con (Successful) 0.479
Prob (Win) 0.452176
The other possibility is one that was already looked at. the PAT is not good, the 2 point conversion is good, and the Giants win in OT.
Event Probability
PAT (Unsuccessful) 0.056
2 pt Con (Successful) 0.479
Overtime (Win) 0.458333333
Prob (Win) 0.012294333
The total probability of the reverse strategy is ~46.4%.
Looking at this more qualitatively, this doesn't make logical sense without even looking at the numbers. In Pat Shurmur's scenario he gives you two shots at a 2 point conversion if one fails, in this scenario he gives you one shot. Another way of looking at it is that if you were to flip the scenarios. In your ideal scenario you kick the PAT and then get a 2 point conversion. Reversed is your ideal scenario of Pat Shurmur's strategy. However, if your idea scenario doesn't work and you make a PAT but miss the 2 pt conversion, you lose. On the flip side, if you miss that 2 pt conversion first, you're not going for the PAT because in that situation you KNOW it won't be enough, you'll go for a 2 pt conversion. You're basically taking away the benefit of knowing how many points will be enough to stay alive in the game go into OT.
Finally, here are the final tallies of probability of winning the game in the three strategies.
Pat Shurmur vs. Conventional Strategy +15.8%
Pat Shurmur vs. Reverse Strategy +11.4%
So mathematically, his strategy was sound.