According to the Pro Football Hall of Fame, as of the start of the 2007 season the team with the best all time regular season winning percentage was the Miami Dolphins whose all time regular season record was 368-252-4 for a winning percentage of .593. Second was the Chicago Bears with an all time regular season record of 670-482-42 for a winning percentage of .579.
As far as all time winning percentages go, through 15 games of the 2009 season that would be the Houston Texans who have an all time regular season record of 48-79 for a winning percentage of .378. The Tampa Bay Buccaneers have the second lowest all time regular season winning percentage at .393 (208-322-1) and the Atlanta Falcons are third lowest at .414 (275-390-6).
As of the start of the 2008 season, the Lions all time regular season record is 488-553-32 for a regular season winning percentage of .470. The Lions all time playoff record is 7-10 for a winning percentage of .412.
Through the 2008 season, Manning's regular season winning percentage is .665 (117-59 record) and his playoff winning percentage is .467 (7-8 record).
Highest Winning Percentage, Regular Season Miami Dolphins .580 Highest Winning Percentage, Overall Dallas Cowboys .577
In regular season games, (if you count the first game of the 2008 season) Brady's overall winning percentage as a starter is .809. Without that start, Tom Bradys career winning percentage is .781. Brady is 14-3 in the playoffs, a .823 winning percentage.
Coming into the 2008 NFL season Roethlisberger's regular season winning percentage was 70.9%. Through the Baltimore Ravens game on December 14, 2008 that percentage had increased to 72.1%. He is 5-2 in the post-season giving him an overall winning percentage of 72.0% as of 12/15/2008.
The Lions best regular season winning percentage came in 1953 when they had a record of 10-2 for a winning percentage of .833. The most wins the Lions had in a regular season came in 1991 when they went 12-4.
Through the 2007 season, the American League team with the most wins in a regular season was the 2001 Seattle Mariners with 116. The American League team with the best winning percentage in a regular season is the 1954 Cleveland Indians who went 111-43 for a winning percentage of .721. Seattle's record in 2001 was 116-46 for a winning percentage of .716.
In MLB as of the start of the 2009 season, the lowest regular season winning percentages are: 1) Tampa Bay Rays: 742-1037 .417 2) San Diego Padres: 2933-3421 .462 3) Texas Rangers: 3570-4059 .468
.636 Winning PrecentageThe 2009 New York Yankees won 103 games and lost 59 during the regular season for a .636 winning percentage.
According to Basketball Reference, the Lakers all time regular season record through the 2007-08 season is 2905-1824 for a winning percentage of .614.
As far as winning percentage goes, the Bulldogs went 1-5 in 1904 and 1905 for a winning percentage of .167. Since they have been playing a regular season of 10 or more games, it is a .273 winning percentage (3-8) in 1953.
Tom Osborne's regular season record in his 25 seasons as head coach of the University of Nebraska was 255-49-3 for a winning percentage of .836. His record in bowl games was 12-13 for a winning percentage of .480.
As of the start of the 2009 season, the Padres' all time regular season record is 2933-3421 for a .462 winning percentage.
As of the start of the 2010 season, the Cowboys have leapfrogged the Miami Dolphins. The Dolphins have a win percentage of .579 and the Cowboys have a .580 percentage.
Through Super Bowl XLII, that has never happened. The lowest regular season winning percentage to win the Super Bowl was .625 (10-6) by the 49ers that won Super Bowl XXIII and the Giants that won Super Bowl XLII.
The top winning percentage of the 1980s in the NFL was the San Francisco 49ers. They won 68.4% of their regular season games. 2nd was the Washington Redskins at 63.8%.
As of the start of the 2008 season, the best franchise regular season winning percentage is .580 for the Miami Dolphins (369-267-4). The Dallas Cowboys are second at .578 (414-302-6).
As of November 02, 2009 it he is 45-27 as a starter, Regular Season and Playoffs, no Pre Season included. That would be 0.625.
The franchise's best winning percentage for a season is .623 and has been accomplished in three seasons. The 1886 Quakers had a record of 71-43 and both the 1976 and 1977 Phillies had a record of 101-61. The 1976 and 1977 teams are the only two teams in Phillies history to win 100+ games in the regular season.The franchise has had two other teams to finish with a winning percentage of .600 or better. The 1899 Phillies had a record of 94-58 for a winning percentage of .618 and the 1887 Quakers had a record of 75-48 for a winning percentage of .610.
The University of Alabama has a 24 game regular season winning streak. Florida has a twenty game regular season winning streak and overall a twenty two game winning streak with one regular season game left.
Statistically speaking, the Philadelphia 76ers of the 1972-73 season has the record for the lowest winning percentage with .110, winning 9 games and losing 73 in that season. In the early NBA, however, the Providence Steamrollers had the worst season in history, winning only 6 games out of 48 played that season.
The Tigers best winning percentage for a regular season came in 1934 when they went 101-53 for a .656 winning percentage. They won the AL pennant but lost to the St. Louis Cardinals in the World Series. The most wins the Tigers had in a regular season is 104 in 1984. They won the AL pennant and defeated the San Diego Padres in the World Series.