The Chiefs/Colts game was crazy, with 89 points scored between the two teams and a 4 touchdown comeback (the 2nd greatest comeback in NFL playoff history, only to this '93 game between the Oilers and the Bills). The Colt's 45-44 victory will be remembered for a long time in Indianapolis and around the league.
With the game being decided by a single point, one might think the game's most important decisions were made in the 2nd half as Indianapolis made their comeback. Indeed, it was quite a monumental collapse by Kansas City. Advanced NFL Stats even looked into the Chiefs' chance of winning if they simply knelt down on every play in the 2nd half. However, there was a play early in the game that could have helped Kansas City get to an even further lead.
The Situation
With the game tied at 7, Kansas City faced a 4th-and-1 at the Colts' 1 yard line. They got to this point from an Alex Smith to Dwayne Bowe 63 yard hookup, but only managed 1 yard on the first 3 downs. Out comes the field goal unit and Ryan Succop kicks a 19 yard field goal to go up by 3. Was it the right move? Was it in fact the "safe" play here?
The Factors
Once again, we will look at the probabilities of success and failure for both a 4th down attempt and a field goal, but also look at what the expected outcome of the next Colts possession would be. To do so, we will break it down into several parts:
1. Chiefs Kick a Field Goal
a. What is the probability of success or failure?
b. What is the expected outcome of the Colts' next drive depending on success or failure?
2. Chiefs Go for It on 4th Down
a. What is the probability of success or failure?
b. What is the expected outcome of the Colts' next drive depending on success or failure?
Since the game is still in the first half, the clock makes much less of a difference. Clearly, if it was a tie game with only 2 seconds left to go, the Chief's would maximize win probability instead of trying to score the most points.
Kicking the Field Goal
Kicking the Field Goal is the "safe" play as most football pundits will tell you. Take the points and get the lead. Of course, you'll have to kick the ball back to the Colts who then get their own drive. A 19 yard Field Goal try is closer than an extra point, so we will estimate chances of success at 100%. That is not true of course. There could be a bad snap, a block, or the kicker could just miss it outright. However, estimating that probability at 100% makes our calculations much easier.
The more difficult calculation involves what the expected outcome of the Colts' next drive is. The Chiefs will have to kick the ball away, and the typical result of a kickoff has been a touchback. Accounting for the possibility of a return of course, puts the Colts in a slightly better position. Lets assume they get the ball on average at their own 25 yard line. The calculator at Advanced NFL Stats figures the expected points of the Colts from this position to be 0.58 points. This of course is an average number. The Colts' offense was ranked 15th in the regular season by yards and 14th by points, so they're not too far from the average in the 32 team league. If you believe the Colts offense to be better (or worse) than this, adjust that 0.58 figure for your own calculations.
Expectation of Kicking the Field Goal
Thus, we can calculate the Chiefs' expectation when kicking the field goal. It will be:
Expected Points (FG) = 100%(3-0.58)
or
Expected Points (FG) = 2.42 points
Going for it on 4th Down
Going for it on 4th down is a little more complicated. We can no longer just assume success, but we have to assign a probability of success. We will also have to again estimate the Colts' expected points on the next drive, given the Chiefs' success or failure.
Probability of Success
On the 1 yard line, the Advanced NFL Stats calculator has the average team succeeding 68% of the time if they go for it. In the exact game played, this number might have actually been lower since star running back Jamaal Charles was out of the game with a concussion suffered earlier. For our estimates, let's move this down to 60% instead of 68% and see where the numbers fall out.
Expected Points of the Colts' Next Drive
Depending on what happens, the Chiefs will either have to kick the ball off after a touchdown, or the Colts will be pinned deep in their own territory after a failed 4th down conversion. We've already estimated the Colts' expected points after a KC touchdown at 0.58. Now, using the Advanced NFL Stats Calculator again, we need to estimate the Colts' expected points when backed up on their own 1 yard line, where we presume they will take over if the Chiefs fail to score a touchdown.
It may be surprising to know that an average team pinned on its 1 yard line expects to score -0.53 points. Meaning, it will be more likely the Chiefs score than the Colts. This has a few reasons behind it. One is the chance of a safety. There won't be a better chance for a defense to score a safety than when the offense is backed way up on their own 1 yard line. And lest I forget, this blog is called Always Go For Two, so I'd certainly cheer on the Chiefs defense if they were to gain a safety. The other factor is the Colts would likely choose to punt at some point on the drive, giving the Chiefs good field position. This isn't an absolute of course, but is something to consider.
For the calculations, we now have to factor in the chance of failure, and assuming a touchdown is worth 7 points here, we get the following calculation:
Expected Points(Go For It) = 60%(7-0.58) + 40%(0 - -0.53)
Expected Points(Go For It) = (0.60)(6.42) + 0.40(0.53)
Expected Points(Go For It) = 3.852 + 0.212
Expected Points(Go For It) = 4.064
As you can see, the expected points for going for it are significantly more than kicking the field goal (67% more in fact).
Conclusion
Given the assumptions we've made, Andy Reid should definitely have gone for a touchdown in this spot. In our case, we even underestimated the chance the Chiefs would punch it in from the 1 yard line here.
What would be the break even point for the Chiefs offense here? Meaning, how bad would the Chiefs offense have to be in order to make kicking the field goal the right move here? If we let x = the Probability of the Chiefs converting the 4th down, we can set the two equations equal to one another:
EP(FG) = EP(Go for It)
(1.00)(3-0.58) = x(7 - 0.58) + (1-x)(0 - -0.53)
2.42 = 6.42x + 0.53 - 0.53x
Combining like terms and subtracting 0.53 on both sides:
1.89 = 5.89x
0.3208 = x
This calculation shows the Chiefs would have to be worse than 32.1% to convert the 4th and 1 before kicking the field goal would be the right play. It would take quite a stretch of the imagination to figure a team ranked 6th in points scored per game in the regular season to NOT have more than a 32% chance of converting here, even with those injuries.
Ultimately, in a game lost by 1 point, this hidden play might have made the difference.
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