Week 5 DVOA Ratings
by Aaron Schatz
The No. 1 team drops and the No. 3 team rises, but we still have the same top three teams in the same order atop the DVOA ratings after Week 5: Los Angeles Rams, Chicago Bears, and Kansas City Chiefs. Then there's a healthy gap between those three teams and the rest of the league.
Underneath the top three teams, the top ten has a number of teams that made healthy jumps this week. New Orleans and the Los Angeles Chargers climb together from No. 11 and No. 12 to No. 4 and No. 5 after two big wins. New England climbs from No 15 to No. 9, and Pittsburgh moves up all the way from No. 21 to No. 10. In the other direction, only one team can really compare with a similar-sized drop: Washington, which plummets from No. 9 to No. 22 after the Saints smashed them all over the Superdome. A week ago, Washington was in the top dozen on both offense and defense; now Washington ranks 20th or worse on both offense and defense.
Although these team jumps are impressive, what's historical about this year is that big gap between the top three teams and the rest of the league. We've seen similar gaps between the top of the league and everyone else, but it's usually one or two teams, not three. At 17.3% DVOA, New Orleans has the lowest rating ever for the No. 4 team after Week 5. The only other year where the No. 4 team at this point was below 20% was 1991, when the Chiefs were No. 4 behind 5-0 Washington and New Orleans plus 4-1 Denver. But that year was one team dominating, since Washington was over 70% and would eventually go on to be the best team DVOA has ever measured.
The unexpected team in the top ten is still the Miami Dolphins, whose DVOA stays roughly the same despite a 27-17 loss to the Cincinnati Bengals. Bear with me a moment, because I'm sort of obsessed with the Dolphins and why our ratings differ from conventional wisdom right now.
First, let's look at why our ratings thought the Dolphins had a better game than the Bengals. On offense/defense, the two teams came out basically the same. Cincinnati gained more yards per play, 5.7 to 5.0, but Miami had a better success rate on offense, 45 percent to 37 percent. That leaves special teams, where the Dolphins came out much better than the Bengals thanks to Jakeem Grant's 71-yard punt return, three Grant kick returns averaging 29.7 yards, and four Matt Haack punts that ended inside the 20. Miami's 24.1% special teams DVOA this week keeps the Dolphins stable in the DVOA ratings. The Dolphins lost the game in large part thanks to two turnovers returned for touchdowns, and the length of turnover returns is not really predictive for future performance.
That brings us back to why the Dolphins were so high going into this week. Most of the value is in their Week 2 and Week 3 wins, for completely different reasons. Week 2 is primarily about the defense, which held the Jets to a 33 percent success rate and forced two interceptions and three fumbles. Week 3 is about big plays on offense, as the Dolphins had just a 38 percent success rate but averaged 9.8 yards per play, the second-highest of any team in any game this year (behind the Rams against the Vikings in Week 4).
The Dolphins are doing different things well each week, except for Week 4 against the Patriots when they did nothing well. Somehow, the mix of plays has turned the Miami DVOA rating into something that's more than the sum of its parts.
Despite Miami's high rating, this week's strong New England performance helped sanity to reestablish itself. The Patriots are now tied with the Dolphins in the standings, and they once again have the higher DAVE rating. So it was a shock when I ran this week's playoff simulation and... we still came out with Miami as a slight favorite to win the AFC East. This time, the culprit is the remaining schedule for each team. Miami's remaining schedule ranks 28th with six games at home. New England's remaining schedule ranks 18th with five games at home.
Overall, I'm still left with a pretty complicated opinion on the Dolphins and how our ratings are treating them. I absolutely think that DVOA is overrating the Dolphins, and that in turn is leading to them being overrated in the playoff odds. (The playoff odds also don't know about New England's recent pattern of overcoming September struggles.) At the same time, I think DVOA is pointing something out that other people might be missing, that the Dolphins are not complete frauds. The defense, in particular, is better than we ever would have expected coming into this season, fifth in DVOA and sixth in success rate allowed.
OK, enough with my Dolphins obsession. Let's go to the top and bottom of the league and update how the Rams and Bills are doing among the best and worst offenses we've ever tracked.
|BEST OFFENSIVE DVOA
THROUGH 5 GAMES, 1986-2018
|WORST OFFENSIVE DVOA
THROUGH 5 GAMES, 1986-2018
One important thing about these historical tables is that DVOA each year is normalized so the average offense is at 0%. That's important for comparing teams in different years because the offensive environment in the NFL has changed so much between, say, the 2000 Rams and the 2018 Rams. You've seen a lot of stats quoted in a lot of places to show just how much offenses have dominated the season so far, but here's another table that demonstrates how extreme the 2018 season has been -- especially when compared to a one-year downturn in 2017 that now looks like a blip in offense's historic march upward.
Every run of DVOA starts with "raw VOA," simply comparing success on each play to the baselines based on multiple years of data. After that, we normalize each year to zero, with different down-and-distance combinations being normalized separately. But take a look at what has happened to that raw VOA over time. With a couple of exceptions, primarily 2013 and 2017, offensive levels and passing levels keep going up and up. Rushing levels, on the other hand, bounce around a bit without any kind of heavy trend. As a result, the passing premium -- the dotted purple line, the difference between passing efficiency and rushing efficiency -- has also grown over time.
Note that this graphic shows defensive VOA rather than offensive VOA, so that only passes and runs are included without having to consider aborted snaps and certain penalties such as false starts.
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A little bit of news as far as how we're computing our various formulas. Based on some preliminary research on how long to consider preseason projections in rating teams into the regular season, I'm changing the percentages we use for DAVE over the next few weeks. This isn't a complete, permanent change, just something to give DAVE more accuracy until I'm able to do full research on changing the percentages. Here's how we'll be changing the percentage of DAVE based on our preseason forecast, compared to what we used to do:
After 5 games: Now 40 percent instead of 27 percent (or in recent years, 30 percent)
After 6 games: Now 30 percent instead of 19 percent
After 7 games: Now 20 percent instead of 8.5 percent
After 8 games: Now 10 percent instead of fully replacing DAVE with weighted DVOA
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These are the Football Outsiders team efficiency ratings through five weeks of 2018, measured by our proprietary Defense-adjusted Value Over Average (DVOA) system that breaks down every single play and compares a team's performance to the league average based on situation in order to determine value over average. (Explained further here.)
OFFENSE and DEFENSE DVOA are adjusted to consider all fumbles, kept or lost, as equal value. SPECIAL TEAMS DVOA is adjusted for type of stadium (warm, cold, dome, Denver) and week of season. As always, positive numbers represent more points so DEFENSE is better when it is NEGATIVE.
Because it is early in the season, opponent adjustments are only at 50 percent strength; they will increase 10 percent every week through Week 10. As always, positive numbers represent more points so DEFENSE is better when it is NEGATIVE.
DAVE is a formula which combines our preseason projection with current DVOA to get a more accurate forecast of how a team will play the rest of the season. Right now, the preseason projection makes up 40 percent of DAVE for most teams (50 percent for teams with just four games played).
To save people some time, please use the following format for all complaints:
<team> is clearly ranked <too high/too low> because <reason unrelated to DVOA>. <subjective ranking system> is way better than this. <unrelated team-supporting or -denigrating comment, preferably with poor spelling and/or chat-acceptable spelling>
- NON-ADJUSTED TOTAL DVOA does not include the adjustments for opponent strength or the adjustments for weather and altitude in special teams, and only penalizes offenses for lost fumbles rather than all fumbles.
- ESTIMATED WINS uses a statistic known as "Forest Index" that emphasizes consistency as well as DVOA in the most important specific situations: red zone defense, first quarter offense, and performance in the second half when the score is close. It then projects a number of wins adjusted to a league-average schedule and a league-average rate of recovering fumbles. Teams that have had their bye week are projected as if they had played one game per week.
- PAST SCHEDULE lists average DVOA of opponents played this season, ranked from hardest schedule (#1, most positive) to easiest schedule (#32, most negative). It is not adjusted for which games are home or road.
- FUTURE SCHEDULE lists average DVOA of opponents still left to play this season, ranked from hardest schedule (#1, most positive) to easiest schedule (#32, most negative). It is not adjusted for which games are home or road.
- VARIANCE measures the statistical variance of the team's weekly DVOA performance. Teams are ranked from most consistent (#1, lowest variance) to least consistent (#32, highest variance).