Doug Miller of MLB.com crunched the numbers and found that since 1995--when MLB expanded to six divisions--66.3 percent of the teams in first place on June 1 have gone on to win the division.
On the surface that sounds like great news for the Yankees, Tigers, Rangers, Phillies, Brewers, and Dodgers. Of course, another way of looking at the numbers suggests that two of those six teams will fall from first place by season's end.
Los Angeles is already eight games up in what is probably baseball's worst division, so the Dodgers look pretty safe. On the other hand, I'd have zero trouble imagining any of the other five June 1 division leaders failing to hang onto their leads all season.
The Yankees have a one-game lead in baseball's best division, the Tigers have the worst record of any first-place team, the Rangers will have to hold off the increasingly healthy Angels, the Phillies and Mets figure to go down to the wire and may also be joined by the Braves, and the NL Central is so tightly bunched behind the Brewers that they have just a four-game lead over the fourth-place team.