To get a feel for which teams are really doing well, and which have just been beating up on weaker teams, we should look at strength of schedule. One of the interesting applications of accounting for opponent strength using a regression model is that offensive and defensive opponent strength can be analyzed separately. We can see which squads have faced the toughest and easiest opposing units so far this year.
The table below lists each team and their to-date opponents' strength ranked from toughest (1) to weakest (32). The table includes overall opponent strength, opponent offensive strength, and defensive oppoenent strength.
| Team | Opp Str | Opp O Str | Opp D Str |
| NO | 1 | 1 | 1 |
| BUF | 2 | 2 | 5 |
| NYG | 3 | 4 | 2 |
| CIN | 4 | 3 | 12 |
| JAX | 5 | 5 | 10 |
| STL | 6 | 8 | 6 |
| CHI | 7 | 20 | 4 |
| MIA | 8 | 10 | 11 |
| SF | 9 | 14 | 18 |
| PHI | 10 | 21 | 8 |
| SD | 11 | 24 | 3 |
| DEN | 12 | 9 | 21 |
| SEA | 13 | 18 | 14 |
| HOU | 14 | 6 | 20 |
| ARI | 15 | 22 | 9 |
| TEN | 16 | 7 | 27 |
| OAK | 17 | 16 | 16 |
| WAS | 18 | 12 | 19 |
| CLE | 19 | 19 | 15 |
| IND | 20 | 25 | 23 |
| MIN | 21 | 23 | 13 |
| ATL | 22 | 17 | 24 |
| NYJ | 23 | 11 | 25 |
| CAR | 24 | 13 | 26 |
| GB | 25 | 26 | 17 |
| BAL | 26 | 15 | 30 |
| DET | 27 | 31 | 7 |
| PIT | 28 | 29 | 29 |
| KC | 29 | 32 | 22 |
| TB | 30 | 28 | 32 |
| NE | 31 | 27 | 31 |
| DAL | 32 | 30 | 28 |
The defensive units that have faced the toughest offenses so far are NO, BUF, and CIN. Look for those defenses to improve if only because they're not likely to face as difficult a schedule as they have so far. Likewise, the teams that have faced the weakest defenses so far are KC, DET, and DAL. They might appear better than they really are.
The offensive units that have faced the toughest defenses so far are NO, NYG, SD, and CHI. The Giants haven't been too bad on offense so far this year, so perhaps they'll put up some bigger numbers when their schedule eases up. NO has started with the most brutal schedule of all 32 teams. The teams that have faced the weakest offenses so far are TB, NE, BAL, PIT, and TEN. Those defenses might be overrated at this point.
By "offense/defense" measures are you just lumping together the measures in the model?
If so, do you know how independent those statistics are? Most of the simple statistics for offense/defense are correlated - a good defense changes the offense, usually resulting in more points/drive, fewer yards/drive, but more points/game and more yards/game (fewer yards to go, but more opportunities). The effect isn't that strong, but it is there.
You could see that by looking at the average "total offense" rating as a function of defense rating.
I'm holding defense equal (average) to measure offense and vice versa. And to adjust for opponent strength, I hold average the opponent's same unit. For example, to measure a team's offense, I hold average its own defense and its opponents' offenses.
The only thing I lose in the process is penalty data, which is not recorded as offensive or defensive, but just total team penalties for and against.
This is all based on efficiency stats (yds/pass att, yds/rush, int/att, etc.). Although there can be significant correlations between points allowed and points scored, and among other stats, there is very little inter-dependence between offense and defensive efficiencies, at least for the past 5 seasons (r=-0.01, n=160). This year appears to buck that trend, with a few teams either good on both sides of the ball or bad on bad on both sides. I think that is mostly luck, given the very low correlation for previous years.
In other words, the yds per pass attempt gained by an offense does not impact the yds per rush or yds per pass attempt allowed by the defense.
By the way, this is one of the reasons I tend to favor the use of an efficiency model. In fact, the original purpose of building the model was to separate offense and defense and identify which is more important to winning. After watching the Ravens defense deliver a short field to their offense for so many years, I figured efficiency was the way to go.
Let me get this straight: you're saying that I should not cut Drew Brees just yet, right?
How much are you accounting for the fact that Bills' opponents look better on offense because they got to play the Bills defense one game? I assume you are...
I use a second-order adjustment process. I calculate adjusted "strengths" for each team and unit. Then I apply the opponent adjustment. Next I recalculate the strengths using the adjusted values. The process converges after only 2 passes.