Parity has been great for NFL fans, who can see their cellar-dwelling team rise to Super Bowl contention in a season, but not so great for network executives, who long for the days when the Dallas Cowboys and Buffalo Bills made four straight trips to the conference championships and brought huge ratings with them.
   Since then, only three teams have made two trips or more, and in the years when they weren’t playing, ratings have declined with occasional spikes for an exciting game.
  No championship game has averaged a 26 household rating or above since 1998, when the Green Bay Packers made their second straight and the Denver Broncos made the first of two.
   That could change this Sunday. On Fox the Philadelphia Eagles enter their third-straight NFC championship after two straight losses, but last year’s game improved 5 percent over the previous year.
  Average ratings for the second-straight year a team plays in the championship game have risen 11.2 percent for games played since 1992.
   The Tennessee Titans just missed playing in their second straight AFC championship with a three-point loss Saturday. The last AFC team to do so, the Denver Broncos in 1998 and ’99, improved their second-year rating 6 percent. The New England-Indianapolis Colts game on CBS should do well, but probably not a huge improvement over last year.
  When there are no repeat teams, the games don’t do so well. The New England Patriots-Pittsburgh Steelers game two years ago was the lowest-rated since at least 1991 despite providing the closest contest in five years.
   That game, which the Patriots won 24-17, averaged a 21.2 household rating. The back-to-back Broncos wins averaged a 24.9 rating and the Bills’ four straight appearances averaged a 25.9.
  The lowest-rated game in the NFC since 1991 was the New York Giants’ 41-0 blowout of the Minnesota Vikings in 2001, which averaged a 20.6 rating. The four Cowboys games from 1993 to ’96 averaged a 33.1 household rating.
   Overall ratings are down 14 percent for the past five years, which have averaged a 23.6 rating, versus the previous five for the AFC championship game, which averaged a 27.5.
   NFC championship ratings have dipped 23 percent in that time, from a 31.08 for 1994-’98 to a 23.9 for 1999-2004.
  In other sports ratings news, the Sugar Bowl averaged a 14.8 rating for ABC last Sunday, the second lowest in the Bowl Championship Series title game history.
   The 2002 game was the only one with a lower rating, a 14.3. This year’s LSU-Oklahoma game was off 14 percent from last year’s 17.2 rating for Miami-Ohio State.
   The NFL wild card game playoffs on ABC averaged a 15.0 household rating, up 3 percent from last year.