2015 NFL Playoffs, Super Bowl Odds

Odds for the 2015 NFL playoff final, presented from the AFC team’s point of view:

SuperBowl Playoff Odds
Prediction Method	AFC Team	NFC Team	Score Diff	Win Prob	Est. Point Spread
C&F Playoff Model	Denver Broncos	Carolina Panthers	2.097	0.891	15.5
Pythagorean Expectations	Denver Broncos	Carolina Panthers	-0.173	0.295	-6.4
Simple Ranking	Denver Broncos	Carolina Panthers	-2.3	0.423	-2.3
Median Point Spread	Denver Broncos	Carolina Panthers	-5.0	0.337	-5.0

 

Last week the system went 1-1, for a total record of 6-4. The system favors Denver more than any other team, and does not like Carolina at all. Understand, when a team makes it to the Super Bowl easily, and a predictive system gave them about a 3% chance to get there in the first place, it’s reasonable to assume that in that instance, the system really isn’t working.

So we’re going to modify our table a little bit and give some other predictions and predictive methods. The first is the good old Pythagorean formula. We best fit the Pythagorean exponent to the data for the year, so there is good reason to believe that it is more accurate than the old 2.37. It favors Carolina by a little more than six points. SRS directly gives point spread, which can be back calculated into a 57.7% chance of Carolina winning. Likewise, using median point spreads to predict the Denver-Carolina game gives Carolina a 66.3% chance of winning.

Note that none of these systems predicted the outcome of the Carolina – Arizona game. Arizona played a tougher schedule and was more of a regular season statistical powerhouse than Carolina. Arizona, however, began to lose poise as it worked its way through the playoffs. And it lost a lot of poise in the NFC championship game.

 

Conference Championship Round, 2015 NFL playoffs

Odds for the third week of the 2015 playoffs, presented from the home team’s point of view:

Conference Championship Playoff Odds
Home Team	Visiting Team	Score Diff	Win Prob	Est. Point Spread
Carolina Panthers	Arizona Cardinals	-1.40	0.198	-10.4
Denver Broncos	New England Patriots	1.972	0.879	14.6

 

Last week the system went 2-2, for a total record of 5-3. The system favors Arizona markedly, and Denver by an even larger margin. That said, the teams my system does not like have already won one game. There have been years when a team my system didn’t like much won anyway. That was the case in 2009, when my system favored the Colts over the Saints. The system isn’t perfect, and the system is static. It does not take into account critical injuries, morale, better coaching, etc.

 

2015 Playoff Notes

The cumulative stats for the 2015 regular season are:

This gives us the basis to generate playoff values based on my playoff formula. Playoff Odds are calculated according to this model:

logit P = 0.668 + 0.348*(delta SOS) + 0.434*(delta Playoff Experience)

and the results are:

2015 NFL Playoff Teams, C&F Worksheet.
NFC
Rank	Name	Home Field Adv	Playoff Experience	SOS	Total Score
1	Carolina Panthers	0.406	0.434	-1.35	-0.51
2	Arizona Cardinals	0.406	0.434	0.456	1.296
3	Minnesota Vikings	0.406	0.0	0.654	1.06
4	Washington Redskins	0.406	0.0	-0.866	-0.46
5	Green Bay Packers	0.0	0.434	0.863	1.297
6	Seattle Seahawks	0.0	0.434	0.769	1.203
AFC
1	Denver Broncos	0.406	0.434	0.727	1.567
2	NE Patriots	0.406	0.434	-0.839	0.001
3	Cinncinnati Bengals	0.406	0.434	0.661	1.501
4	Houston Texans	0.406	0.0	-0.828	-0.422
5	Kansas City Chiefs	0.0	0.0	0.564	0.564
6	Pittsburgh Steelers	0.0	0.434	0.696	1.130

 

The total score of a particular team is used as a base. Subtract the score of the opponent and the result is the logit of the win probability for that game. You can use the inverse logit (see Wolfram Alpha to do this easily) to get the probability, and you can multiply the logit of the win probability by 7.4 to get the estimated point spread.

 

For the first week of the 2014 playoffs, I’ve done all this for you, in the table below. Odds are presented from the home team’s point of view:

First Round Playoff Odds
Home Team	Visiting Team	Score Diff	Win Prob	Est. Point Spread
Minnesota Vikings	Seattle Seahawks	-0.143	0.464	-1.05
Washington Redskins	Green Bay Packers	-1.757	0.147	-13.0
Cinncinnati Bengals	Pittsburgh Steelers	0.371	0.591	2.75
Houston Texans	Kansas City Chiefs	-0.986	0.271	-7.30

 

So the system suggests that Minnesota – Seattle should be close, perhaps unbettable. Cinncinnati-Pittsburgh is an even match, with Cinncinnati’s factors amounting to a typical home field advantage. Houston-Kansas City and Washington-GB are predicted to be easy wins for the visiting team.