The knowledge that the Rams offense faced a very easy schedule of defensive opponents is just one part of understanding why the 2003 Rams were a team driven more by defense than by offense. Look at the game-by-game results of the 2003 St. Louis Rams, and you get an even clearer demonstration of how the defense, not the offense, was the superior unit, and the one with more responsibility for the team's victories. This is one place where DVOA definitely exposes some of the bias that is inherent in conventional NFL statistics.
The usual numbers -- especially points scored and allowed -- often confuse a good offense for a good defense and vice versa. When a defense is consistently putting the offense in good field position to score, the offense will score. How does the defense put the offense into good position? Through stopping the opposing team, and through turnovers. And turnovers, well, if one word summarized the Rams entire season it would be "turnover." Here is a table showing the top teams in turnovers, both giveaways and takeaways, during the 2003 season:
Top 6 Takeaways Top 6 Giveaways
STL 46 STL 39
BAL 41 BAL 38
NWE 41 NYG 38
KAN 37 ARI 36
MIA 36 BUF 34
SFO 36 MIA 34
As you can see, the Rams were pretty far ahead of the rest of the NFL when it came to taking the ball from their opponents, and that led to a lot of good field position opportunities for the offense to score. At the same time, the Rams also led the league in turning the ball over themselves, which led to a lot of situations where the defense faced an offense which was more likely to score because it was getting the ball in good field position. If the offense is consistently turning the ball over to the other team in your territory, even the best defense is going to have trouble preventing a few touchdowns.
So now let's look at each game the Rams played in 2003, remembering the importance of these turnovers, separating the offense from the defense to see which unit performed better. Here is a table which includes the offensive, defensive, and special teams DVOA for each game, with comments as well: