As far as MLB is concerned, winning percentage doesn't really enter in to whether a team makes the playoffs or not. A team makes the playoffs by winning their division or being the team with the highest winning percentage of those other teams that did not win their division. There have been teams to make the playoffs with a record as 'poor' as 83-78, as did the 2006 St. Louis Cardinals who went on to win the World Series. There have been teams with records as good as 94-68 (1982 Baltimore Orioles) that did not make the playoffs. That goes to show that a team with a winning percentage of just over .500 can make the playoffs where a team with a winning percentage of .580 can miss the playoffs.