One third of MLB teams won 90 regular season games in 2011, and all but one of them --the Red Sox -- made the playoffs. Each of last year's 90-win teams enters the 2012 season with hopes of repeating or building on their success, but at least one or two of those nine clubs will probably regress this year.
Some of last year's contenders, such as the Phillies and Yankees, have room for error. They will contend in 2012 even if their win total drops by five or ten games, especially since the MLB playoffs are expanding this year. Which of these 2011 contenders is most likely to struggle in 2012: