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Home Field Advantage and Team Efficiency Stats

Posted by Jason Lisk on November 13, 2007

I'm going to take a look at home field advantage, and whether a team's offensive and defensive passing or rushing efficiency stats have any relationship. When I use the term "home field advantage", or "HFA" here, what I really mean is "the difference between the advantage of playing at home, and the disadvantage of playing on the road." But that does not exactly flow off the tongue, so just know that not every thing that creates the difference has to do with the home field or characteristics of the home team.

Also, while the team efficiency stats (which you can find on each team's page as well as the yearly team stats pages) are not perfect, but they are much better than looking at raw yardage numbers. For example, if a team is averaging 4.0 yards a carry, does this mean the team is consistently gaining 4 to 5 yards on a lot of attempts, or that the team is more like a 3.5 yards per carry team, but one with a few big runs boosting the numbers? We cannot answer that as to any particular team, but it is better than nothing. With that in mind, let's look at what team characteristics might be tied to increasing or decreasing home field advantage.

I looked at all teams that finished between 6-10 and 10-6 since Jacksonville and Carolina joined the league (1995-2006). My choice of those records is partially arbitrary-- I could have just as easily narrowed it to 9-7/7-9, or expanded it to 11-5/5-11. But my goal was to look at the middle class of the NFL, teams that generally have some strengths but also some flaws. I felt this dividing line would accomplish that.

For each team, I then looked at the home/road splits in record, and compared it to the team's offensive yards per rush attempt, offensive yards per pass attempt, defensive yards allowed per rush attempt, and defensive yards allowed per pass attempt.

210 total teams finished between 6-10 and 10-6 during the 12 seasons reviewed, an average of over 17 per season--so slightly more than half the teams in the league on average. The entire population averaged 0.586 win percentage at home and 0.417 win percentage on the road, for a +0.169 difference. This would equate to +1.36 more home wins than road wins over the course of a 16 game schedule for the average team.

Two of the categories showed no correlation with changes in home field advantage. These were offensive yards per rush attempt, and defensive yards allowed per pass attempt. Within this population, as both team offensive yards per rush attempt and defensive yards allowed per pass attempt improved, the team's winning percentage, both home and road, improved. However, the differences between home and road stayed fairly constant.

Which leads to the other two categories. Let's start with the stronger of the two, defensive rush yards allowed per attempt. I divided the 210 teams into five roughly equal tiers based on rush defense: excellent (3.6 ypa or lower), above average (3.7 to 3.9), average (4.0 to 4.1), below average (4.2 to 4.4), and poor (4.5 or higher). Here are the home/road splits in winning percentage:

category    no.     home          road          difference
===============================================
excellent   43      .606          .395          +.211
above avg   50      .614          .403          +.211
average     37      .622          .416          +.206
below avg   41      .537          .419          +.117
poor        39      .548          .460          +.088
===============================================

It looks like a direct relationship between rush defense and home field advantage, as the better run defenses show an above average home/road difference, while the below average defenses have small splits.

Here are the pass offense numbers, sorted by excellent (7.5 or more ypa), above average (7.1 to 7.4), average (6.7 to 7.0), below average (6.3 to 6.6) and poor (6.2 or lower).

category    no.     home          road          difference
===============================================
excellent   34      .614          .471          +.143
above avg   36      .608          .429          +.179
average     45      .574          .424          +.150
below avg   50      .578          .396          +.182
poor        35      .568          .382          +.186
===============================================

These numbers are not nearly as pronounced as the rush defense. There is some tendency for pass offense to be inversely related to home field advantage, as the excellent group is a little below average in home/road difference, and the below average and poor groups perform above average in that respect. However, when we cross-reference rush defense and pass offense, two types of teams emerge that show significant differences in home field advantage.

Fifty-two teams had both an above average or excellent rush defense (3.9 or fewer yards allowed per rush attempt) and a below average or poor pass offense (6.6 or fewer yards per pass attempt). These run stopping, poor passing teams combined to win .604 at home and only .363 on the road, for a difference of +.241. That equates to almost two more home wins than road wins per season on average.

17 of the 52 (32.7%) had at least 3 more home wins than road wins. Only three of these teams finished a season with more road wins than home wins (and all finished with exactly one more road win).

At the opposite end of the spectrum, there were thirty-five teams that finished with a below average or poor rush defense (4.2 or more yards allowed per rush) and an above average or excellent pass offense (7.1 or more yards per pass attempt). These "good passing, can't stop the run" teams won .561 at home and .473 on the road, for a difference of +.088. That is an average of +0.70 more wins at home a season.

Only 6 of the 35 (17.1%) "good passing, can't stop the run" teams won at least 3 more home games than road games. Of these six, three came from Kansas City and Denver, two of the strongest home field advantages in the league. The other three were from dome teams (Detroit 1995, Minnesota 2003, Saint Louis 2004), two of which play in a division with outdoor cold weather rivals.

Almost half of these teams (17 of 35) finished with at least as many road wins as home wins. The 1997 Bengals and 2000 Saints both finished with 4 more road wins than home wins.

If the strength of rush defense does increase home field advantage, there is a potential explanation. If a team is better at stopping the run, it is conceivable that such a team would be somewhat more likely to place its opponent into more 3rd and long situations. This might translate to a bigger advantage at home, where the offense is subject to crowd noise, than on the road, where the home crowd would presumably be quiet to aid the offense. On the other hand, relatively poor passing offense could increase the road disadvantage, for much the same reasons.

This entry was posted on Tuesday, November 13th, 2007 at 4:50 am and is filed under Home Field Advantage. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.