Interesting post, David. Got me thinking about parity.
In terms of winning percentage over the last five years, we have this:
+------+------------+-------------+----------------+| team | years | num_seasons | win_percentage |+------+------------+-------------+----------------+| clt | 2004--2008 | 5 | 0.788 || nwe | 2004--2008 | 5 | 0.788 || pit | 2004--2008 | 5 | 0.700 |...| sfo | 2004--2008 | 5 | 0.313 || det | 2004--2008 | 5 | 0.263 || rai | 2004--2008 | 5 | 0.250 |+------+------------+-------------+----------------+Let's look at the previous 5-year chunks:
Code:
+------+------------+-------------+----------------+| team | years | num_seasons | win_percentage |+------+------------+-------------+----------------+| ram | 1999--2003 | 5 | 0.700 || oti | 1999--2003 | 5 | 0.700 || clt | 1999--2003 | 5 | 0.638 |...| crd | 1999--2003 | 5 | 0.313 || cin | 1999--2003 | 5 | 0.300 || htx | 1999--2003 | 2 | 0.281 |+------+------------+-------------+----------------+
So we have two teams better than the #1 team from 99--03 and two teams worse than the worst team from 99--03. The same is true if we look back another five years:
Code:
+------+------------+-------------+----------------+| team | years | num_seasons | win_percentage |+------+------------+-------------+----------------+| sfo | 1994--1998 | 5 | 0.763 || gnb | 1994--1998 | 5 | 0.713 || den | 1994--1998 | 5 | 0.675 |...| cin | 1994--1998 | 5 | 0.350 || rav | 1994--1998 | 3 | 0.344 || ram | 1994--1998 | 5 | 0.325 |+------+------------+-------------+----------------+
[yeah, I know, the Ravens should be counted with the old Browns]Here is 1989--1993:
+------+------------+-------------+----------------+| team | years | num_seasons | win_percentage |+------+------------+-------------+----------------+| sfo | 1989--1993 | 5 | 0.775 || buf | 1989--1993 | 5 | 0.725 || oti | 1989--1993 | 5 | 0.638 |...| crd | 1989--1993 | 5 | 0.313 || tam | 1989--1993 | 5 | 0.300 || nwe | 1989--1993 | 5 | 0.238 |+------+------------+-------------+----------------+1984--1988:
Code:
+------+------------+-------------+----------------+| team | years | num_seasons | win_percentage |+------+------------+-------------+----------------+| chi | 1984--1988 | 5 | 0.784 || sfo | 1984--1988 | 5 | 0.742 || den | 1984--1988 | 5 | 0.678 |...| det | 1984--1988 | 5 | 0.310 || atl | 1984--1988 | 5 | 0.296 || tam | 1984--1988 | 5 | 0.241 |+------+------------+-------------+----------------+
1979--1983
Code:
+------+------------+-------------+----------------+| team | years | num_seasons | win_percentage |+------+------------+-------------+----------------+| dal | 1979--1983 | 5 | 0.721 || mia | 1979--1983 | 5 | 0.674 || rai | 1979--1983 | 5 | 0.665 |...| nyg | 1979--1983 | 5 | 0.370 || nor | 1979--1983 | 5 | 0.351 || clt | 1979--1983 | 5 | 0.274 |+------+------------+-------------+----------------+
1974--1978
Code:
+------+------------+-------------+----------------+| team | years | num_seasons | win_percentage |+------+------------+-------------+----------------+| rai | 1974--1978 | 5 | 0.784 || pit | 1974--1978 | 5 | 0.768 || ram | 1974--1978 | 5 | 0.757 |...| nyg | 1974--1978 | 5 | 0.289 || nor | 1974--1978 | 5 | 0.288 || tam | 1974--1978 | 3 | 0.152 |+------+------------+-------------+----------------+
Here is the standard deviation of team winning percentages for each of those 5-year blocks:
Code:
+------------+-------------+| Years | STD_win_pct |+------------+-------------+| 1974--1978 | 0.170 || 1979--1983 | 0.101 || 1984--1988 | 0.133 || 1989--1993 | 0.133 || 1994--1998 | 0.113 || 1999--2003 | 0.117 || 2004--2008 | 0.130 |+------------+-------------+
So over the last five years the league has been more spread out, in terms of semi-long-term haves and have-nots, than it was in the ten years prior. And it's comparable to how it was in the late 80s and early 90s, when the 49ers roamed the earth.Here are the best 5-year winning percentages since 1950:
Code:
+------+------------+---------+----------------+| team | years | record | win_percentage |+------+------------+---------+----------------+| nwe | 2003--2007 | 66-14-0 | 0.825 || mia | 1971--1975 | 57-12-1 | 0.821 || mia | 1970--1974 | 57-12-1 | 0.821 || cle | 1950--1954 | 49-11-0 | 0.817 || cle | 1951--1955 | 48-11-1 | 0.808 || clt | 1964--1968 | 55-12-3 | 0.807 || rai | 1973--1977 | 56-13-1 | 0.807 || rai | 1972--1976 | 55-13-2 | 0.800 || gnb | 1962--1966 | 54-13-3 | 0.793 || rai | 1967--1971 | 53-12-5 | 0.793 |+------+------------+---------+----------------+
And the worst:
Code:
+------+------------+---------+----------------+| team | years | record | win_percentage |+------+------------+---------+----------------+| tam | 1983--1987 | 16-63-0 | 0.203 || oti | 1982--1986 | 16-57-0 | 0.219 || tam | 1985--1989 | 18-61-0 | 0.228 || tam | 1982--1986 | 17-56-0 | 0.233 || nwe | 1989--1993 | 19-61-0 | 0.238 || cin | 1998--2002 | 19-61-0 | 0.238 || rai | 2003--2007 | 19-61-0 | 0.238 || tam | 1984--1988 | 19-60-0 | 0.241 || oti | 1970--1974 | 16-52-2 | 0.243 || oti | 1981--1985 | 18-55-0 | 0.247 |+------+------------+---------+----------------+