There has been a lot of talk about the Seattle Seahawks defense this year and a lot of discussion about the strength (or relative weakness) of their opponents in terms of offensive ability. Well I wanted to look at this a different way. So often we look at who teams play, we don’t look at their relative defensive ability, how well they hold opposing below their season averages. By doing this we look at a teams ability to stop a team from reaching their mean success on offense. By looking at a defense this way we are able to get a better image of how strong a defense is and it weakens the impact of playing a strong of weak schedule. Now the always amazing Chase Stuart look at this in a similar way but didn’t quite look at it from this angle, but if you are craving more stats on this, he has a great read on it here.
Warning: Sortable Tables and Intense Numbers Ahead
But we’ll look at this 3 ways, first we’ll look at the top defenses in NFL history purely by the numbers, with their abbreviations in ():
– Points per Game Allowed (PPG)
– Interceptions (INT)
– Interception Divided by Attempts + Sacks (INT %)
– Sacks (Sack)
– Sacks Divided by Attempts + Sacks (Sack %)
– Net Passing Yards per Attempt Allowed (Pass NY/A)
– Rushing Yards per Attempt Allowed (Rush Y/A)
– Yard per Play Allowed (YPP)
– Passing Touchdowns Allowed (Pass TD’s)
– Passing Touchdowns Divided by Attempts + Sacks (Pass TD %)
I didn’t look at rushing TD’s since that is a hard thing to judge since a team can play great defense but opposing teams could be 1st and Goal on the 1, run 3 times and get in.
In these tables I took the top 50 defenses of all time and we’ll see how Seattles stacks up (I removed #49 and #50 since they were so far behind the rest it wasn’t even comparable so really it’s a top 48 list, confusing, sorry) against the all time greats in these categories.
I then included each teams average rank, so there are 10 categories so this is their rank in each category divided by 10.
Next we’ll look at each of these categories and how well they hold opposing teams below their season averages. For example, over the course of the season they play teams that average 25 points per game scoring, but they hold all those teams to an average of 15 points per game, they allow 10 fewer points per game than their opponents average. We’ll look at this for all the categories.
*To be clear, things like points or yards allowed, negative is good, it means holding teams below their average. Things like interceptions and sacks are meant to be positive, if you average 5 more sacks over the course of the season than the average, that’s a good thing, same for interceptions.*
The final way we’ll look at this is by percentage. Let’s use the team we mentioned above, their opponents averaged 25 points a game, they allowed an average of 15 points a game, so they allow 40% fewer points than their opponents average. We’ll use the same formula across the board and then give an average rank again.
This stuff isn’t for the statistical faint of heart, so be ready.
While the Seahawks have played weaker offenses, when removing that factor, they still rank very high among the great defenses in history. They are easily among the top secondaries in NFL history, averaging 93% more interceptions than their opponents averaged, and ranked very well, coming in at 18th overall (higher among passing categories) among the 48 all time greats in this study in terms of difference percentage. This defense is for real, regardless of opponents ability, they had a great season.
This table is actually worth it’s own post regardless of the Seahawks because we could have an entire discussion about the other teams on this list and who had the best defense ever. The matchup between Denver and Seattle will be a very interesting game, I know I can’t wait.