As of the start of the 2008 season, the Philadelphia Philles have lost the most games in MLB history. Their franchise record is 8853-10028 for a winning percentage of .469. The team with the worst franchise winning percentage is the Tampa Bay Rays who have a record of 645-972 for a winning percentage of .399.
The 1986 New York Mets had a record of 108-54 for the highest winning percentage in franchise history with .667.
Highest Winning Percentage, Regular Season Miami Dolphins .580 Highest Winning Percentage, Overall Dallas Cowboys .577
Click on the 'All Time Winning Percentages' link on this page to see a listing of teams and their franchise winning percentage as of the start of the 2007 season.
its the New York Yankees
15 in 2001
The Cleveland Brown's all time historical winning percentage was .535 which has topped the franchise's winning record and is high against other NFL teams.
In the history of the franchise, 1901 - 2012, the New York Yankees have 9,862 wins, 7,493 losses for a .568 winning percentage.
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.
All time the Chicago Bears hold the most wins in football history at 704 and the best winning percentage at .579.
From 1901 when the franchise was called the Baltimore Orioles through 2009 the New York Yankees have a record of 9,575 wins 7,294 losses for a .568 winning percentage.
Yes, they are one of the better NFL teams, though not winning a super bowl, have a .555 franchise winning percentage. 5th highest in the NFL