THE CHALKBOARD
Myth Busters: The
1991 Philadelphia Eagles Defense
Every year around the time the Sloan Sports Conference takes place in Boston,
somebody makes a bold pronouncement that leaves the 'Ol QuantCoach scratching
his head and asking, "Could that be accurate?"
A great example is this statement from Football Outsiders' Aaron Schatz, who,
after looking at all NFL teams since 1950 and doing some calculations and
estimations, wrote:
"[T]he 1991 Eagles are the best defense for now and it's
not even close. The 1969 edition of the Purple People Eaters, who came in
second, are closer to 35th than they are to first."
That's some strong sauce.
It's also utterly bogus.
The measure of NFL defense is not complicated. The purpose of defense is to a)
take downs from the other team and b) take the ball from the other team. That's
it. That's all a defense has to do to be successful. Because downs are
resources, an opponent cannot manufacture production without downs. It's even
harder for an opponent to manufacture production if it does not have the ball.
QC's defensive play design statistic is one measure of how effectively a
defense takes an opponent's downs. Below are NFL defenses (and one AFL defense)
that have been among the best in history at taking downs from their opponents.
Here is how the 1991 Eagles compare:
Rank
|
Year
|
Team
|
Nickname/
Design(er)
|
D Play Design
|
Record
|
Playoff Result
|
| 1. |
1969 |
Vikings |
Purple People Eaters |
.1228 |
12-2 |
SB Runner-up |
| 2. |
1977 |
Cowboys |
Doomsday D |
.1354 |
12-2 |
SB Champs |
| 3. |
1961 |
Chargers |
Fearsome Foursome |
.1372 |
12-2 |
AFL Runner-up |
| 4. |
1982 |
Dolphins |
Killer B's |
.1429 |
7-2 |
SB Runner-up |
| 5. |
1975 |
Steelers |
Steel Curtain |
.1431 |
12-2 |
SB Champs |
| 6. |
2008 |
Steelers |
LeBeau Fire Zone |
.1453 |
12-4 |
SB Champs |
| 7. |
2002 |
Buccaneers |
Tampa-2 |
.1495 |
12-4 |
SB Champs |
| 8. |
1963 |
Bears |
George Allen Zone |
.1529 |
11-1-2 |
NFL Champs |
| 9. |
1962 |
Packers |
Phil
Bengston |
.1531 |
13-1 |
NFL Champs |
| 10. |
1976 |
Steelers |
Steel Curtain |
.1543 |
10-4 |
Div. Champs |
| 11. |
1996 |
Packers |
Fritz Shurmur |
.1547 |
13-3 |
SB Champs |
| 12. |
1972 |
Dolphins |
No Name D |
.1564 |
14-0 |
SB Champs |
| 13. |
1991 |
Eagles |
Buddy Ryan |
.1622 |
10-6 |
No playoffs |
| 14. |
2013 |
Seahawks |
Legion of Boom |
.1637 |
13-3 |
SB Champs |
| 15. |
1985 |
Bears |
Da Bears 46 |
.1672 |
15-1 |
SB Champs |
| 16. |
2000 |
Ravens |
Marvin Lewis |
.1732 |
12-4 |
SB Champs |
The 1991 Eagles defense
was championship caliber, to be sure, but QC easily found a dozen defenses in
less than an hour who took downs from their opponents better than the 1991
Eagels. Moreover, the best defense on QC's list, the 1969 Vikinigs who came in
second on Football Outsiders, is about 1.25 percent better than the runner-up,
Tom Landry's 1977 version of the Doomsday Defense. The idea that the best
defense in NFL history could be almost 10% better than the next best defense is
ridiculous. The NFL is a nearly perfectly competitive environment. It is simply
impossible for the best defense to be 10 percent better than the second best
defense if those defenses are measured against a common standard, here a
10-yard gain.
How did the 1991 Eagles do at taking the ball away from their opponents? Again,
they did very well, but, again, not the best in NFL history. Here is a table of
the same teams above and the number of takeways per game each obtained:
Rank
|
Year
|
Team
|
Nickname/
Design(er)
|
Takeaways/Game
|
| 1. |
1961 |
Chargers |
Fearsome Foursome |
4.71 |
| 2. |
1963 |
Bears |
George Allen Zone |
3.86 |
| 3. |
1962 |
Packers |
Phil Bengston |
3.57 |
| 4. |
1985 |
Bears |
Da Bears 46 |
3.38 |
| T5. |
1972 |
Dolphins |
No Name D |
3.29 |
| T5. |
1976 |
Steelers |
Steel Curtain |
3.29 |
| 7. |
1969 |
Vikings |
Purple People Eaters |
3.23 |
| 8. |
2000 |
Ravens |
Marvin Lewis |
3.06 |
| T9. |
1982 |
Dolphins |
Killer B's |
3.00 |
| T9. |
1991 |
Eagles |
Buddy Ryan |
3.00 |
| 11. |
1975 |
Steelers |
Steel Curtain |
2.64 |
| T12. |
2013 |
Seahawks |
Legion of Boom |
2.44 |
| T12. |
1996 |
Packers |
Fritz Shurmur |
2.44 |
| 14. |
2002 |
Buccaneers |
Tampa 2 |
2.38 |
| 15. |
1977 |
Cowboys |
Doomsday D |
2.21 |
| 16. |
2008 |
Steelers |
LeBeau Fire Zone |
1.81 |
Conededly, turnovers
were far more prevalent in the pre-Bill Walsh era before the NFL instituted
major rule changes in 1979. But the 1985 Bears and the 2000 Ravens still took
the ball a little better than the 1991 Eagles did among post-Walsh era
teams.
Finally, if you look behind the numbers, the 1991 Eagles defense looks a little
more suspect. More than 42 percent of the passes thrown agains the Eagles in
1991 were thrown by quarterbaks who were undistinguished at best: Don
Majkowski, Tom Tupa, Bubby Brister, Steve Walsh, Donald Hollas, Stan Gelbaugh,
Steve Beuerlein, and Jeff Rutledge.
When the 1991 Eagles faced Mark Rypien, who led Washington to a Super Bowl win
that year, they struggled. Cleveland's Bernie Kosar also was very effective
against Philadelphia but the Browns defense blew a 23-0 lead in a 32-30 loss.
Tampa Bay's Chris Chandler threw 2 fourth quarter touchdown passes to rally the
Bucs to a 14-13 win after relieving a struggling Vinny Testaverde.
Finally, the best quarterback the 1991 Eagles faced, San Francisco's Steve
Young, threw just 15 passes on a day all he had to do was be content to let the
mistake-prone Philadelphia offense (5 turnovers) beat itself.
The 1991 Eagles were a very, very good, championship-caliber defense.
But Mr. Schatz's statement that they are the best defense in NFL history and
"it's not even close" is pure hyperbole.
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