Memorial Day (especially when it was celebrated on May 30) has always meant the true start of the pennant races; it just so happens that it coincides with the one-third point of the season, and by now some trends are clear, early leaders have been established, and there are unexpected surprises, both hopeful and disappointing. Today we’ll concentrate on the hopeful.

Coming into the season, the traditional order in the American League East seemed ripe for change. The Boston Red Sox suffered through a miserable, 93-loss season in 2012, and were dismantled from top to bottom; their nemesis the New York Yankees seemed old, infirm, and incapable to realizing the potential of a $220-million payroll loaded with non- or under-performing assets. Surprise, surprise: the Red Sox are in first place, although that may change by the time the current weekend series ends. The Yankees are hot on their heels with a lineup that often looks like a collection of scratch-and-dent pickups from a second-hand store. Put them in pinstripes, and they perform. Right behind them are last year’s dark horse, the Baltimore Orioles, who continue to interpose themselves; and the Tampa Bay Rays have overcome a deficiency in what was supposed to be a strength, starting pitching, and are also in easy striking distance. We’re highlighting the upbeat stories today, remember.

The American League Central was supposed to be a cakewalk for the defending champion Detroit Tigers, but the revamped Cleveland Indians have melded free-agent pickups and auspicious trades with the managerial savvy of Terry Francona. They have yet to get the memo about conceding the division to Jim Leyland’s Bengals.

The American League West saw a sudden coup on the last day of the season in 2012 when the upstart Oakland Athletics usurped the throne from the two-time champion Texas Rangers. The Rangers are on top so far with the best record in the AL, and don’t seem to miss at all their superstar Josh Hamilton or team stalwart Michael Young, neither of whom have enjoyed much success in their new missions. Don’t forget about the A’s, though, who suffer through much in their dreadful ballpark yet reward their loyal fans with winning baseball.

The story is similar in the National League: the Atlanta Braves started hot, cooled off, and are playing well again holding a decent lead over last year’s NL East champions, the Washington Nationals. The Nats have yet to gel this season, but they are in the race and must be considered.

The NL Central has the best team in MLB, the St. Louis Cardinals, but the Cardinals have been unable to shake last year’s champions, the Cincinnati Reds, or the resurgent Pittsburgh Pirates. Both of those teams are right in the mix and both would make the playoffs as of today.

In the National League West, the revamped Arizona Diamondbacks hold a thin lead over the 2012 World Series Champion San Francisco Giants, and the Colorado Rockies are still holding up after a dreadful season. The middle third of the season, basically now through September 1, will tell the tale of contenders and pretenders.