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Parity III

Posted by Doug on August 17, 2006

In this post I'll discuss the kind of parity that, juding from the comments on the last two posts, most people seem to be interested in. Also, while it will take great effort for me to refrain from offering my opinion of football's parity situation compared to major league baseball's, I will keep the focus on the NFL and how its parity has changed through its recent history.

And in general I want to make it clear that I place no value judgements on parity, at least none that I want to talk about here. For now, my only objective is to place the facts before you. I apologize for lack of text that will accompany these tables; this is a busy time of year for me.

First let's look at every four-year period for every franchise since the merger. Here are the best and worst such periods, measured by average regular season wins normalized to a 16-game season:


TM Years Avg Adj Wins
==========================
mia 1971-1974 13.6
mia 1972-1975 13.4
oak 1974-1977 13.4
chi 1985-1988 13.2
sfo 1989-1992 13.0
oak 1973-1976 13.0
min 1973-1976 13.0
sfo 1987-1990 13.0
ram 1973-1976 12.7
chi 1984-1987 12.7
mia 1982-1985 12.6
mia 1981-1984 12.5
pit 1972-1975 12.4
dal 1975-1978 12.4
pit 1975-1978 12.4
sfo 1984-1987 12.3
dal 1976-1979 12.3
was 1982-1985 12.3
rai 1982-1985 12.3
ram 1975-1978 12.3
oak 1972-1975 12.3
sfo 1994-1997 12.2
buf 1990-1993 12.2
oak 1975-1978 12.2
dal 1992-1995 12.2
dal 1977-1980 12.2
pit 1973-1976 12.1
ram 1974-1977 12.1
min 1974-1977 12.1
sfo 1986-1989 12.1
gnb 1995-1998 12.0
dal 1991-1994 12.0
phi 2001-2004 12.0
sfo 1990-1993 12.0
nwe 2001-2004 12.0
sfo 1988-1991 12.0
sfo 1992-1995 12.0
sfo 1995-1998 12.0
ind 2002-2005 12.0
.
.
.
atl 1987-1990 4.0
cin 1999-2002 4.0
det 2001-2004 4.0
buf 1983-1986 4.0
nor 1974-1977 4.0
sdg 1972-1975 4.0
sfo 1977-1980 3.9
buf 1984-1987 3.9
hou 1971-1974 3.9
hou 1983-1986 3.8
bal 1979-1982 3.7
nyg 1973-1976 3.6
tam 1984-1987 3.6
cin 1991-1994 3.5
nwe 1990-1993 3.5
nwe 1989-1992 3.5
bal 1981-1984 3.5
hou 1981-1984 3.4
tam 1985-1988 3.3
tam 1983-1986 3.0
hou 1982-1985 2.9

Obviously, there is some overlap in the groupings that makes this chart a bit tough to interpret, but a quick eyeballing indicates that the recent group of teams who have achieved sustained regular-season success --- New England, Philadelphia, Indianapolis --- look pretty weak compared to the dyansties of old. Several different franchises had better four-year runs in the 70s and 80s. Likewise, as ugly as the recent Lions, Cardinals, and Bengals have been, their fans have got it good compared to several teams in the 70s and 80s.

Now let's look at the number of teams in each four-year period whose average number of wins would be within one game of .500 and within two games of .500. (To be precise, I am declaring them to be "within 1 game of .500" if their average winning percentage during the period was between 6/14 and 8/14, and "within 2 games" if it was between 5/14 and 9/14. Although it doesn't matter too much. I opted for "within 1 in a 14-game season" rather than "within 1 in a 16-game season" so as not to skew the percentages toward the recent era.)


Period % within 1 % within 2
========================================
1970-1973 19.2 50.0
1971-1974 34.6 53.8
1972-1975 30.8 46.2
1973-1976 26.9 46.2
1974-1977 19.2 46.2
1975-1978 15.4 57.7
1976-1979 32.1 57.1
1977-1980 25.0 64.3
1978-1981 42.9 78.6
1979-1982 50.0 78.6
1980-1983 50.0 75.0
1981-1984 42.9 75.0
1982-1985 39.3 71.4
1983-1986 25.0 60.7
1984-1987 35.7 60.7
1985-1988 32.1 75.0
1986-1989 39.3 67.9
1987-1990 39.3 75.0
1988-1991 39.3 71.4
1989-1992 28.6 71.4
1990-1993 25.0 60.7
1991-1994 42.9 71.4
1992-1995 39.3 67.9
1993-1996 40.7 66.7
1994-1997 44.4 77.8
1995-1998 44.8 79.3
1996-1999 40.0 76.7
1997-2000 46.7 73.3
1998-2001 46.7 90.0
1999-2002 41.9 74.2
2000-2003 29.0 74.2
2001-2004 45.2 80.6
2002-2005 56.2 75.0

Wow. From 1998 to 2001, 90% of all teams were within two games of .500. That can't be right, can it?


TM 1998 1999 2000 2001 Avg
=============================================
mia 10- 6-0 9- 7-0 11- 5-0 11- 5-0 10.2
min 15- 1-0 10- 6-0 11- 5-0 5-11-0 10.2
stl 4-12-0 13- 3-0 10- 6-0 14- 2-0 10.2
ten 8- 8-0 13- 3-0 13- 3-0 7- 9-0 10.2
gnb 11- 5-0 8- 8-0 9- 7-0 12- 4-0 10.0
nyj 12- 4-0 8- 8-0 9- 7-0 10- 6-0 9.8
den 14- 2-0 6-10-0 11- 5-0 8- 8-0 9.8
oak 8- 8-0 8- 8-0 12- 4-0 10- 6-0 9.5
tam 8- 8-0 11- 5-0 10- 6-0 9- 7-0 9.5
jax 11- 5-0 14- 2-0 7- 9-0 6-10-0 9.5
bal 6-10-0 8- 8-0 12- 4-0 10- 6-0 9.0
pit 7- 9-0 6-10-0 9- 7-0 13- 3-0 8.8
nyg 8- 8-0 7- 9-0 12- 4-0 7- 9-0 8.5
sfo 12- 4-0 4-12-0 6-10-0 12- 4-0 8.5
nwe 9- 7-0 8- 8-0 5-11-0 11- 5-0 8.2
sea 8- 8-0 9- 7-0 6-10-0 9- 7-0 8.0
buf 10- 6-0 11- 5-0 8- 8-0 3-13-0 8.0
was 6-10-0 10- 6-0 8- 8-0 8- 8-0 8.0
ind 3-13-0 13- 3-0 10- 6-0 6-10-0 8.0
atl 14- 2-0 5-11-0 4-12-0 7- 9-0 7.5
phi 3-13-0 5-11-0 11- 5-0 11- 5-0 7.5
kan 7- 9-0 9- 7-0 7- 9-0 6-10-0 7.2
chi 4-12-0 6-10-0 5-11-0 13- 3-0 7.0
dal 10- 6-0 8- 8-0 5-11-0 5-11-0 7.0
nor 6-10-0 3-13-0 10- 6-0 7- 9-0 6.5
ari 9- 7-0 6-10-0 3-13-0 7- 9-0 6.2
det 5-11-0 8- 8-0 9- 7-0 2-14-0 6.0
car 4-12-0 8- 8-0 7- 9-0 1-15-0 5.0
sdg 5-11-0 8- 8-0 1-15-0 5-11-0 4.8
cin 3-13-0 4-12-0 4-12-0 6-10-0 4.2

Note that 10.2/16 is less than 9/14, so the only teams outside the range are the three at the bottom. Also note that only teams that were around for all four years are included. Hence, no Browns.

So the 90% figure is a bit flukish, but still, that's a lot of parity. Compare it to the 1975--1978 period:


TM 1975 1976 1977 1978 Avg
==============================================
dal 10- 4-0 11- 3-0 12- 2-0 12- 4-0 12.4
pit 12- 2-0 10- 4-0 9- 5-0 14- 2-0 12.4
ram 12- 2-0 10- 3-1 10- 4-0 12- 4-0 12.3
oak 11- 3-0 13- 1-0 11- 3-0 9- 7-0 12.2
min 12- 2-0 11- 2-1 9- 5-0 8- 7-1 11.4
den 6- 8-0 9- 5-0 12- 2-0 10- 6-0 10.2
mia 10- 4-0 6- 8-0 10- 4-0 11- 5-0 10.2
bal 10- 4-0 11- 3-0 10- 4-0 5-11-0 10.1
was 8- 6-0 10- 4-0 9- 5-0 8- 8-0 9.7
stl 11- 3-0 10- 4-0 7- 7-0 6-10-0 9.5
nwe 3-11-0 11- 3-0 9- 5-0 11- 5-0 9.3
cin 11- 3-0 10- 4-0 8- 6-0 4-12-0 9.3
hou 10- 4-0 5- 9-0 8- 6-0 10- 6-0 9.1
chi 4-10-0 7- 7-0 9- 5-0 7- 9-0 7.5
det 7- 7-0 6- 8-0 6- 8-0 7- 9-0 7.2
cle 3-11-0 9- 5-0 6- 8-0 8- 8-0 7.1
sdg 2-12-0 6- 8-0 7- 7-0 9- 7-0 6.5
atl 4-10-0 4-10-0 7- 7-0 9- 7-0 6.5
phi 4-10-0 4-10-0 5- 9-0 9- 7-0 6.0
gnb 4-10-0 5- 9-0 4-10-0 8- 7-1 5.8
sfo 5- 9-0 8- 6-0 5- 9-0 2-14-0 5.6
nyg 5- 9-0 3-11-0 5- 9-0 6-10-0 5.2
buf 8- 6-0 2-12-0 3-11-0 5-11-0 5.0
nyj 3-11-0 3-11-0 3-11-0 8- 8-0 4.6
kan 5- 9-0 5- 9-0 2-12-0 4-12-0 4.4
nor 2-12-0 4-10-0 3-11-0 7- 9-0 4.3

Finally, just for the sake of completeness, here is the standard deviation of four-year average wins for all teams in each four-year period.


Period StDev of avg wins
=============================
1970-1973 6.95
1971-1974 6.40
1972-1975 7.88
1973-1976 8.21
1974-1977 8.06
1975-1978 7.10
1976-1979 5.86
1977-1980 5.04
1978-1981 3.19
1979-1982 2.95
1980-1983 3.20
1981-1984 4.54
1982-1985 5.54
1983-1986 6.20
1984-1987 5.85
1985-1988 4.60
1986-1989 4.29
1987-1990 4.05
1988-1991 4.09
1989-1992 5.07
1990-1993 5.48
1991-1994 4.51
1992-1995 4.33
1993-1996 3.67
1994-1997 3.73
1995-1998 3.54
1996-1999 3.28
1997-2000 3.33
1998-2001 2.83
1999-2002 3.54
2000-2003 3.92
2001-2004 3.52
2002-2005 3.43

Well, what do you know, it looks like we're going to need a Parity IV, because I haven't even started talking about the playoffs yet.

This entry was posted on Thursday, August 17th, 2006 at 4:06 am and is filed under General, History. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.