These rankings were inspired by Paul Dalen‘s take on ranking total offenses and defenses. Instead of looking at total yards generated per game offensively or total yards given up defensively (statistics which do not account for the strength or weakness of opponents), he compared a team’s yards gained or given up to the team’s opponents’ average number of yards given up or gained. This number resulted in a percentage of expected yards gained or given up.
For example, if the blue team averages 400 yards per game and the red team holds them to 350 yards, the red team gave up 87.5% of expected yardage. Apply this concept to the season as a whole and you have a better way to rank total offense and defense by now accounting for the quality of the opponent.
I decided to take this same principle and apply it to points for and points against. Unfortunately, I didn’t have the time to compare all 125 teams, so I chose to just look at the Pac-12.
Here are the average points for and against for the Pac-12 as of week 9 games.
|TEAM||AVG PTS FOR||TEAM||AVG PTS AGAINST|
|9||Washington St||30.9||9||Oregon St||27.4|
Based on the above data, if you were an Oregon State fan, let’s say, you might say that Oregon State has the third-best scoring offense in the conference. I would argue that you are wrong. The numbers above do not account for quality of opponent at all. Colorado, for example, has played two I-AA teams while Stanford hasn’t played any.
Following Paul Dalen’s example, we’ll take the points scored and given up and compare them to teams’ opponents’ average points given up and scored for an expected points percentage. For example, if the green team scores 35 points against the yellow team and the yellow team is giving up on average 28 points a game, the green team’s expected points percentage would be 125% (they scored 125% of the number of points they were expected to score based on their opponent’s average). Apply that concept to the whole season and these percentages will give a better representation of scoring offense and defense.
EXPECTED POINTS FOR % (SCORING OFFENSE)
|TEAM||% OF EXPECTED POINTS FOR|
The above table shows that, on average, Arizona State is scoring 192% of expected points (i.e. 192% of their opponents’ average points given up per game) while USC is scoring only 95% of expected points (making opposing defenses look better than they have all season). I would now say to the Oregon State fan that his team has the fifth-best scoring offense in the conference.
If you just look at points per game, Arizona is fourth in the conference while Washington is sixth. What that doesn’t factor in is the fact that Washington has played the top two teams in the conference, while Arizona has not. By looking at percentage of expected points, we get a better comparison with Washington now at third and Arizona behind them.
EXPECTED POINTS AGAINST % (SCORING DEFENSE)
|TEAM||% OF EXPECTED POINTS AGAINST|
On average, Stanford on defense is holding teams to 57% of their average points scored per game while Cal is giving up 116% of teams’ average PPG.
With these two expected points percentages (offense and defense), we can now add the differences from 100% (e.g. ASU offense: 192% – 100% = 92%, ASU defense: 100% – 87% = 13%, ASU overall: 92% + 13% = 105%) for an interesting way to get an overall ranking of the teams in the conference.
COMBINED DIFFERENCES (EXPECTED POINTS FOR + EXPECTED POINTS AGAINST)