Every NFL season is a long and grueling 16 games. Things change so rapidly that predicting what will happen next is virtually impossible. It's what makes sports so compelling.
The fact that the Kansas City Chiefs won two games last year and are 7-0 this year is just the latest example of how unpredictable the NFL can be. It's not that the rebound was totally unexpected, but no one expected them to be undefeated at this point with such a suffocating defense.
Before the season started, there was some debate about how imposing Kansas City's defense could be in 2013. The consensus was "very good," but seven weeks later, it's now safe to say the Chiefs could have the best defense since the 2000 Baltimore Ravens.
That may seem like a crazy comparison, and by the end of the season, it may be undeserved. There are nine games left on the schedule, so caution should be exercised before finalizing this grandiose comparison.
But here are the facts: 55 teams have allowed 81 points or fewer through seven games like the Chiefs, and none have since 2006.
In this explosive era of offense, a case could be made that not only is the 2013 Chiefs defense better than the 2000 Ravens defense, but so were several other defenses over the past decade.
The Traditional Approach
The 2013 Chiefs don't quite compare to the 2000 Ravens defensively if we only look at raw statistics without adjusting for eras or opponents. This is the typical comparison that glosses over several key factors, but it's an interesting starting point.
The Ravens only allowed 10.3 points per game overall and 10.7 points per game through seven games, compared to the Chiefs' 11.6. The 2013 Chiefs are roughly two field goals worse than the 2000 Ravens using these numbers.
|2013 Chiefs vs. 2000 Ravens Comparison Through Seven Games|
|Pro Football Reference|
Yards is another common comparison, but yards per play is a more accurate measure of the performance of the defense than total yards. The 2000 Ravens allowed 4.3 yards per play and 4.5 yards per play through seven games, compared to the Chiefs, who have allowed 4.8 yards per play. That's approximately a 20-yards-per-game difference.
As far as touchdowns allowed, the 2000 Ravens allowed seven through seven games—one fewer than the 2013 Chiefs. The 2000 Ravens also had three more takeaways through seven games than the 2013 Chiefs.
One area where the 2013 Chiefs are vastly superior is sacks. The Chiefs have 35 sacks in 2013, and the 2000 Ravens only had 35 all season.
Football Outsiders has been using a metric called DVOA (Defense-adjusted Value Over Average) to better understand team performance since 1989. According to DVOA, the Ravens didn't even have the best defense in 2000—the Tennessee Titans did. Since 2000, eight teams have had a better defense than the 2000 Ravens, according to DVOA.
The 2000 Ravens had a DVOA of minus-23.8, which is minus-4.5 better than the 2013 Chiefs. At least according Football Outsiders, the 2013 Chiefs aren't nearly as good as the 2000 Ravens.
|2013 Chiefs vs. 2000 Ravens Advanced Statistical Comparison|
|Football Outsiders, Advanced NFL Stats|
It's important to note that DVOA is a statistic that can be used to compare teams in different years because it's adjusted based on the success or failure of the opponent in that year. If you are a big believer in DVOA, the argument could stop here.
EPA, or Expected Points Added, is another advanced statistic that can be revealing. EPA boils down the results of every play to determine the point impact of that play. Advanced NFL Stats has this data going back to 1999.
The 2013 Chiefs have an EPA of minus-56.1, but we'll have to use a little guess work to compare that with 2000 Ravens since those stats are for a 16-game season. Thankfully, Advanced NFL Stats has broken it down per play.
The Chiefs have an EPA per play of minus-0.12 compared to the minus-0.18 of the 2000 Ravens. A very rough estimate using these numbers would tell us that the 2000 Ravens were between two and four points per game better than the 2013 Chiefs.
Using the advanced statistics, the Ravens came out way ahead of the Chiefs—even more so than the traditional stats.
The reason traditional stats are popular is that they are easy to understand. No one needs to tell you what total yards or points per game means. The team with more points at the end of the game wins—it's really that simple. However, it's not fair to compare statistics like this from year to year with zero adjustment.
|2013 Chiefs vs. 2000 Ravens Opponent Comparison|
|Team||NFL Avg. PPG||Opp. PPG||Opp. PPG vs. NFL||Opp. PPG Games 8-16|
|Pro Football Reference|
Strength of opponent and the difference in overall offensive output are the adjustments that are applicable in this situation. To keep it simple, we're only going to examine points per game allowed.
There have been 11.7 percent more points scored across the NFL through seven games in 2013 than there were through seven games in 2000. That 2013 Chiefs have only allowed 8.4 percent more points per game than the 2000 Ravens, so the rise in the offensive output of the league accounts for the difference.
Of course, that isn't specific to the schedule each team faced. Strength of schedule is sometimes why we see teams falter late in the season or make a strong push for the playoffs. A comparison here is applicable because the Ravens were able to produce for 16 games, while the Chiefs have only played nine.
The 2013 Chiefs have faced opponents who have scored 27.3 percent more points on average than the 2000 Ravens. Remove the games against the two teams in question, and the difference is 32.1 percent.
|Points Allowed vs. Opponent Points Per Game|
|Stats||2013 Chiefs||2000 Ravens||Diff.|
|Opp. PPG vs. Team||11.6||10.7||-0.9|
|Opp. PPG vs. NFL||21.0||15.9||+5.1|
|Opp. PPG Games 8-16||25.5||16.9||+8.6|
|Pro Football Reference|
The teams that have played the 2013 Chiefs have scored 19.6 points per game against the other teams they have faced, but only 11.6 against the 2013 Chiefs. The 2000 Ravens' opponents only scored 15.4 points per game against teams through Week 7, so the Chiefs have faced tougher offenses.
In addition to facing better offenses, the Chiefs are holding opponents 8.0 points per game under their season average and 9.4 under what they have scored against other teams. The Ravens only held their first seven opponents 4.7 points lower than their season averages at the time and 5.2 points under their average against other teams.
It sure seems like the 2013 Chiefs are actually doing a better job than the 2000 Ravens at shutting down offenses; they have just faced better ones. Perhaps the 2000 Ravens are only a measuring stick for great defenses because they won the Super Bowl with a lackluster offense.
In fact, the 2002 Tampa Bay Buccaneers may actually have had the best defense in the last two decades. The best defense of all time is certainly debatable, but at least through seven games, it appears as though the Chiefs belong in the conversation.
Here's the problem for the Chiefs: They face a much more difficult schedule in the second half of the season. Even if they continue to hold opponents 9.4 points per game below their season averages for the final nine games, they will finish the season allowing roughly 14 points per game based on the current offensive production of teams on their schedule.
Although that would still be a very impressive feat by the Chiefs, they wouldn't even be the best defense in the last five years. The 2008 Pittsburgh Steelers allowed 13.9 points per game, and they won the Super Bowl that year.
As we know, things are going to continue to change. The Denver Broncos and San Diego Chargers may see their offensive production come down in the second half, and the Chiefs play them a total of four times.
Currently, the opponents for the final nine games are averaging 25.5 points per game. Compare that with the final nine opponents against the 2000 Ravens that averaged only 16.9 points per game, and you can see how the Ravens were able to sustain their defensive production.
There is danger in trying to project performance from the first seven games over the final nine because of how much things can change, but even with a tougher schedule, the Chiefs could finish with one of the better defenses we have seen in the last five years.
Unfortunately for the Chiefs, the second-half schedule could take them out of the conversation with the great defenses of the last 20 years, which is the kind of defense that could carry them deep into the playoffs. It's very possible that the Chiefs don't even finish the season with the No. 1 scoring defense.
The Chiefs have managed to stay healthy when compared to other teams, especially on defense. Health will continue to play a key role in how this defense finishes, but Kansas City has at least put itself in the "best defense" discussion.
Unless otherwise noted, all statistics via Pro Football Reference.
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