Note: This post was originally posted on the UC Irvine Sports Analysis Collective blog, but is posted here as well.
With the NFL playoffs kicking off on Saturday, it’s going to be an exciting weekend. Let’s break down the two Saturday games.
Kansas City Chiefs- Indianapolis Colts
The Chiefs scored an average of 26.9 points per game and allowed 19.1 points per game during the regular season. However, using Football Outsider’s Defensive Value Over Average metric for both offense and defense and fitting a regression model (download data here), the Chiefs “truly should” have scored 24.2 points per game and allowed 21.7 points per game. The Colts scored an average of 24.4 points per game and allowed 21.0 points per game during the regular season. By DVOA, the Colts should have scored 24.6 points per game and allowed 23.7 points per game.
To obtain the predicted points for each team, I averaged the amount the offense scored with the amount the opposing defense allowed. On a neutral field, we would expect the Chiefs to score 23.95 points and the Colts to score 23.15 points. Kansas City scores 7.5 more points per game on the road and allows 3.5 points less, while Indianapolis Colts score 0.9 points more per game at home and allow 0.2 points per game less at home. To correct for this, we’ll take (7.5 + 3.5)/2, so add 5.5 points to the Chiefs. We’ll add a total of (0.9 + 0.2)/2, or .55, points to the Colts. That totals 29.45 for the Chiefs and 23.7 for the Colts.
However, there are other things that need to be taken into account, factors that could indicate a team will “regress” to a truer form than we have seen. Teams on average recover 50 percent of fumbles over large sample sizes, and a deviation from there indicates that a team is either lucky or unlucky. The Chiefs have recovered over 68 percent of fumbles on the road this season, while the Colts have recovered 51 percent of fumbles at home. The Chiefs recovery rate is unsustainable, and indicates that they may not be as good as their record indicates. The Chiefs also have averaged 2.4 less turnovers than their opponents per game while on the road, and have thrown interceptions on only 0.77 percent of pass attempts on the road, both incredibly better than the league average. Indianapolis is +0.8 turnovers per game at home, better than the league average, and interceptions on 2.41 percent of pass attempts, about the league average.
On special teams, Kansas City makes 82 percent of field goal attempts on the road, but only 33 percent in the last three games. Indianapolis makes 87 percent and has made 90 percent in the last three games. Indianapolis attempts 2.5 field goals to Kansas City’s 1.7 per game. In addition, the Colts average only 4.1 penalties per game (3.0 in the last three games) compared to 6.3 for the Chiefs (5.3 in the last three).
Prediction: Using DVOA alone to determine true ability, these teams are even. The Chiefs are better on the road than at home, which seems to give them a slight edge. However, field goals and penalties may be key in this indoor game, and both edges go to the Colts. The Chiefs are not likely to keep up the turnover rate, and will struggle to win the turnover battle on the road. Colts 28, Chiefs 24.
New Orleans Saints – Philadelphia Eagles
I used the same regression model as mentioned above to figure out expected points scored and allowed. New Orleans scored 25.9 points per game and allowed 19.0 points per game, but “should have” scored 27.6 points per game and allowed 21.9 points per game. Philadelphia scored 27.6 points per game and allowed 23.9 points per game, but should have scored 29.4 points per game and allowed 24.7 points per game. Averaging it out, we would expect 26.15 for New Orleans and 25.65 for Philadelphia. New Orleans scores 16.2 points less and allows 6.8 points more on the road. So, to correct, we take away (16.2 + 6.8)/2, or 11.5 points from the Saints. Philadelphia scores 7.2 less points at home than on the road, but allows 8 points less at home. Thus we’ll add a total of (8 – 7.2)/2, or 0.4 points to the Eagles. That puts the totals at 14.65 for the Saints and 26.05 for the Eagles.
For other factors, the Eagles have won the turnover battle by one turnover per game over their last three games, and are at +0.8 per game on the season. The Saints are even on the season, but have lost the turnover battle by one turnover a game over their past three games. The Eagles have recovered only 43 percent of fumbles on the season, but 52 percent at home. They have recovered only 28 percent in the past three games, a sign of being unlucky to end the season. The Saints have recovered an even 50 percent on the road this season, but none in their last three games, a sign of unluckiness as well. New Orleans has thrown interceptions on 2.65 percent of pass attempts on the road this season, but on 3.03 percent of passes in the last three games. Philadelphia has thrown interceptions on 3.1 percent of pass attempts at home, but only 1 percent in the last three games. Both teams averaged 5.9 penalties per game this season, but New Orleans has averaged 7 per game in the last three games compared to 5.7 for Philadelphia.
In terms of play style, Philadelphia is run-heavy team, rushing on 47 percent of plays for the season and 49 percent of plays at home. New Orleans has rushed on only 36 percent of plays for the season, and 33 percent on the road. The Eagles lead the league in rushing while the Saints are 25th. Both teams have converted field goals at a rate in the mid-70 percent range for the season, but Philadelphia has not missed a field goal in the last three games while New Orleans has only converted 60 percent in that span. Both of these aspects will be critical with the harsh conditions.
Prediction: Both teams are evenly matched in terms of ability, but New Orleans is greatly diminished away from home. With rough weather, the ability of the Eagles to run the ball effectively will play a large role. This will reduce turnovers and penalties, which are in Philadelphia’s favor. Philadelphia 27, New Orleans 20.