It amazes me that even though they are ranked #1 in the NFC, the Eagles continue to be underdogs in all their playoff games (80 percent of NFL experts are picking the Vikings to beat the Eagles in Philadelphia, per NFL Pick Watch). Obviously the loss of their star quarterback, Carson Wentz, in week 14 of the season has affected their standing in the eyes of bookmakers. If you look at just the average score each team allows/produces over the course of the season, you can start to see why many experts would favor the Vikings (graph below).
Both teams have great defenses that seem to be getting better at the end of the season (at least as far as points allowed per game), with the Vikings defense slightly better, allowing a league low 16.4 points/game and the Eagles defense allowing 18.1 points/per game up to this point in the NFL season. The amount of points on average both offenses score is also different, with the Vikings scoring ~24 points/game to the Eagles 27.5 points/game at this point in the season. The average amount of points the Vikings offense scores has been pretty consistent since week 11, but the Eagles offense’s average scoring output has decreasing steadily since around week 14 of the season. Based on strictly scoring averages, I’d say the Vikings defense is better than the Eagles defense, and while the Vikings offense seems to be stable, the Eagles offense appears to be in free-fall towards the end of the season.
If you separate each team’s production home and away, the story changes (graph below). Instead of using the average amount of points a team gives up/scores in a given game, I use how many points a team gives up/scores relative to their overall average based on who they were playing that week (for example, we’d expect a team to score more points against the Browns than we would against the Vikings). If we focus on the defense, the Eagles allow 3 points less than expected at home compared to allowing 1 point less then expected for away games for the Vikings defense (top left section of the graph). If you look at the p-values on the significance of this home/away effect (lower left corner of the graph), the Eagles have the most significant home advantage out of all the teams remaining in the playoffs (Eagles defense has a p-value of 0.01, followed by the Jaguars defense with a home effect p-value of 0.10, and then the Vikings offense with a p-value of 0.14). Based on these metrics, I’d say that the Eagles defense will be better this Sunday than the Vikings defense, but only because they are playing in Philadelphia.
When you look at the offenses, both teams are about the same when you compare points above or below the home and away averages for the Eagles and the Vikings respectively (top right corner of the above graph). As of week 20, the Eagles offense typically scores -0.2 points below expected when playing at home while the Vikings offense typically scores -0.9 less then expected when playing away. As I mentioned before, the Vikings have a relatively low p-value for the home and away effect (p=0.14), so I believe they do play worse on the road (lower right corner of the graph). Combine this with the tendency of the Eagles defense to play better at home, and I think the Eagles have a good chance of scoring more points then the Vikings on Sunday.
When looking at the number of turnovers for each team (above graph), the Eagles both take and give away more turnovers than the Vikings, especially when they’re playing at home. (Against the Falcons last week, the Eagles turned the ball over twice compared to the zero turnovers for the Falcons). Based on these curves, the Eagles defense is predicted to get ~0.2 more turnovers than the Vikings defense, but the Eagles offense is predicted to turn the ball over ~0.4 more times than the Vikings defense at home. If the Vikings have a chance in this game, I would expect them to capitalize on this turnover difference.
When looking at the average amount of sacks the Eagles and the Vikings get/give up over the season, the Eagles home defense and the Vikings away defense are about the same (~2.3 sacks/game by week 20). There is a difference in the home and away averages for the offenses, with the home team usually giving up around 2 sacks per game and the visiting team’s offense giving up on average 2.5 sacks per game. It is possible that the Eagles ability to pressure the quarterback more in the form of sacks could lead to more turnovers and therefore a more balanced ratio between the teams.
Based on all my calculations, I would predict a close game but the Eagles should win by about 3 points at the end of the contest (19.1 to 16.2). The Eagles defense should be able to put pressure on the Vikings quarterback that should keep the turnover ratios between the teams about the same. The Eagles offense at home should be comparable to the Vikings offense away, and therefore the difference will be a better Eagles defense at home than the Vikings. I also have the Patriots winning at home against the Jaguars (23.4 to 17.9), but I think the margin of victory will be less than the current 8.5 points advantage the odds-makers are giving to the Patriots.
-Michael Edwards, Bioinfo Solutions LLC
* Microsoft Excel for Mac 2011 and JMP Pro ver.13 were used to collect, analyze and display NFL data.