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Brian Nemhauser·
Advanced StatsDefense
··8 min read

Battle Of The Best: 2013 Seahawks Defense vs. 1985 Chicago Bears

There have been many stories about what defense stands as the best in the history of the NFL. This series intends to trump them all. The 2013 Seattle Seahawks defense belongs in the conversation for all-time great defenses, but it is unclear exactly how they compare to the legendary 2000 Ravens, 1985 Bears, the vaunted Pittsburgh Steel Curtain and others. One-by-one, I will examine the 2013 Seahawks versus titans of years gone. We will look at numbers that compare apples-to-apples as best as we can across generations and rule changes. It is not clear where the Seahawks stand as we begin. The goal is to be objective and to enjoy the battle. Next up, Mike Singletary and the 1985 Chicago Bears.


Previous Articles In Series:

Ground Rules:

  • No player comparisons: Generalities about players are irrelevant because they are just opinion. Number of Pro Bowlers or Hall of Famers often reflects popular opinion more that actual talent. Should someone want to quantify the quality of each player at each position and aggregate the total talent, I would love to read it. Until then, we will look at the whole team performance.

  • Relative > Absolute: A team that holds opponents to 11.4 points per game (ppg) sounds better than a team that holds opponents to 14.2 ppg. But when the average offense scored 15 ppg in the year of the first team and the average offense scored 27 ppg in the year of the second team, the judgment should shift. We will heavily slant toward how the team performed in the era/year in which they played. This will also help to account for rule changes.

  • Quality of opponent matters: A team that has the best opponent scoring average in the league, and does it during a year when scoring is way up sounds dominant. But what if they played in the 2005 NFC West? Who you play, and how you perform against those opponents needs to be taken into account.

  • Strength of offense: A defense that has to make up for a horrible offense gets extra credit. We will compare the offenses these defenses played with at a high level.

  • Championships: It should not be the ultimate arbiter, but it does have to be factored in. A defense that ends the year as a champion deserves credit for the ultimate accomplishment, and one that fails in that game deserves additional scrutiny. 

  • Analysis versus facts: I will give my opinion at the end of each article about which defense was superior and why. You may come to a different conclusion. The facts should not be disputable. My interpretation of them is open to debate.

Round 1: Yards Allowed

Team League Avg Yards/Game Opponent Yards/Game Std Dev League Rank
1985 Bears 329.4 258.4 -2.19 1
2013 Seahawks 348.5 273.6 -1.95 1
The Bears allowed fewer absolute yards per game and their performance was stronger relative to their peers of that season. Even though the league averaged 20 more yards of offense per game during the Seahawks season, there was a wider spread of offensive performance in 2013, so the standard deviation was larger. The difference between the 2013 Broncos offense (457.3 ypg) and the 2013 Bucs offense (277 ypg) gives you an idea of how varied offenses were. The best offense in yardage in 1985 was the Chargers (408.4 ypg), while the worst was the Lions (279.8). Given the tighter coupling, the Bears defense stood out more in this aspect.

Looking at gross yards allowed gives an overview, but it is important to look at yards surrendered per play. A defense that is on the field longer because their offense cannot move the ball will face more plays and more total yards allowed. They should not be penalized for it.

Team League Avg Yards/Play Opponent Yards/Play Std Dev
1985 Bears 5.0 4.4 -1.8
2013 Seahawks 5.34 4.4 -2.1

Seattle gains a strong advantage when isolating on efficiency per play. They did this despite the same broader spread of offensive performance noted above. That makes this result even more impressive. The Seahawks exit this round with the slightest of edges. We may revisit this after seeing the results comparing the offenses of both teams.

Round 2: Points Allowed

  
Team League Avg Points/Game Opponent Points/Game Std Dev League Rank
1985 Bears 21.5 12.4 -2.4 1
2013 Seahawks 23.4 14.4 -2.1 1

The Bears hold a distinct advantage in both absolute and relative points allowed. The league averaged a coupe of more points per game last season than it did in 1985, and the Seahawks allowed a couple of more points. But relative to the norm of that season, the Bears stood out more. Again, though, let’s look at this on a per play basis.

Team League Avg Points/Play Opponent Points/Play Std Dev
1985 Bears 0.328 0.210 -2.33
2013 Seahawks 0.360 0.233 -2.05

This time, the Bears advantage holds. They were a more efficient and special scoring defense than the Seahawks. Seeing exactly who each team played, and how the defenses performed against that specific competition will be particularly important in this battle.

Round 3: Schedule

Up to this point, we have been comparing the two defenses performance against league averages. But neither the Seahawks nor the Bears played every opposing offense in the league. We need to get specific about which offenses they played, and how they did relative to the averages of those offenses.

Team Aggregate Opponents PPG Opponent PPG Std Dev
1985 Bears 21.2 12.4 -3.3
2013 Seahawks 22.1 14.4 -2.5

The Bears 16 regular season opponents scored an average of 21.2 points per game, nearly identical to the league average (21.5). Seattle faced opponents who averaged slightly below the league average (23.4). Chicago destroyed their competition, and left Seattle in the dust as well by this measure. Not only were they more efficient when comparing to the standard of the year they played in, but they were more efficient against the specific teams they played, and by a sizable margin.

Let’s step away from the regular season for a moment though and just see how both teams did against the best offenses in the league that year. The best versus the best.

Team GMs VS TOP 10 OFF (incl playoffs) +/- Opp Avg
1985 Bears 6 -12.6
2013 Seahawks 3 -19.9

Chicago faced six of the best offenses in the league, including the 4th-ranked Dolphins, 5th-ranked 49ers, 6th-ranked Giants (playoffs), 7th-ranked Jets, and the 10th-ranked Patriots twice (once in the Super Bowl). They held those two teams to a combined 11.8 points per game, less than they regular season average. When the Bears played the best offenses in the league, their defense played even better. That is a testament to their dominance, talent, and competitive nature.

The Seahawks faced the top-ranked, highest scoring offense in the history of football in the Super Bowl, and held them to 8 points. If this was versus the top eleven offenses instead of the top ten, the Seahawks would have had six games against those teams, closing the gap with the Bears.

The Bears game up a total of 10 points in the playoffs. They shutout the Giants and the Rams before bludgeoning the Patriots in the Super Bowl 46-10. Seattle faced higher-powered offenses in the playoffs, and stepped up their game against the best offenses they played.

Still, the Bears regular season performance relative to their competition and dominant playoff run gives them another win in this round.

Round 4: Takeaways

Team League Avg Takeaways/Game Takeaways/Game Std Dev League Rank
1985 Bears 2.4 3.38 2.55 1
2013 Seahawks 1.6 2.4 2.29 1

Both teams led their league in takeaways. In fact, these are among the rarest of defenses that finished the season ranked #1 in points allowed, yards allowed and takeaways. Seattle was the first to accomplish that since the ’85 Bears. Even though the league averaged significantly more takeaways in 1985, the Bears were the more dominant defense in terms of taking the ball from the opponent. Seattle is in in the range from a standard deviation perspective, but there is no doubt the Bears win this round.

Round 5: Offenses

Let’s take a look at just how much help or harm the other side of the ball did to these defenses. Admittedly, I will not go is deep here or else this would turn into an equally long assessment of each offense. Instead, we will stick to some absolute numbers and get some relative information via league rankings.

Team OFF PPG OFF PPG Rank OFF YDS/GM OFF YDS/GM Rank TO/GM TO/GM Rank
1985 Bears 28.5 2 364.8 7 1.94 5
2013 Seahawks 26.1 8 339 17 1.19 4

Chicago was blessed with one of the greatest running backs of all-time, and had a bona fide top five offense that year. Ranked second in the NFL in scoring, the Bears threw it to Willie Gault for long touchdowns and ran it with Walter Payton or even The Fridge. The Bears defense definitely got more help from this offense than the Seahawks defense did from theirs. This solidifies the Seahawks win in round one in terms of yardage. They were forced to carry more of the load, and still were more efficient in that measure. It also closes the gap on some of the other rounds, but not enough to change any of the results.

Seattle’s defense gains some ground in this round. 

Winner: 1985 Chicago Bears

These are two of the best defenses to ever play, but unless you believe the difference in their respective offenses was enough to heavily skew the numbers, the Bears were the better unit. They were close on yards, and clearly ahead in nearly all the other measures. Seattle’s biggest edge was their offense was weaker, and no defense should win based on that.  

Hats off to the Bears.

Keep an eye out for round three of the Battle of the Best when the Seahawks will take on the 2002 Tampa Bay Buccaneers.