Pennant races heating up: A look back at 6 important weekend series

With the MLB postseason six weeks away, let's take stock of how teams ranked before and after this past weekend's crucial sets, and how they may impact October.

Athletics vs. Astros

It's incredible to remember that Oakland was 11 1/2 games back of first place as recently as June 24. Less than two months later, the A's had a shot at taking the AL West lead over the Astros, and nearly did. Before Houston avoided the sweep with Sunday's victory, the two clubs were tied for the top spot. With the AL Central completely sown up, and the AL East essentially settled, the Astros and Athletics have become the premier rivalry in the American League.

Brewers vs. Cardinals

While the standings stayed ostensibly the same in the National League Central, the Cardinals began the series 1 1/2 games back of the Brewers and shrunk the gap to half a game with one in hand, briefly taking over second place before Sunday's game. Furthermore, Milwaukee held sole possession of the second wild-card spot, but are now precariously clustered with the Rockies, Phillies, and Braves for those final two spots, with St. Louis hot on their heels.

Dodgers vs. Mariners

The Dodgers are just emerging from a minor slump where they lost five straight. Outscoring the Mariners 27-7 while winning two of the three games this weekend, Los Angeles still has a legitimate shot at winning the division. But the streaking Diamondbacks and Rockies certainly aren't making it easy.

Diamondbacks vs. Padres

Arizona is maintaining their place atop the division thanks to winning three of four against the Padres. However, one week ago, the D-Backs were trying to distance themselves from the Dodgers. Now, it's the Rockies right behind them with one game in hand.

Rockies vs. Braves

Colorado finished off a remarkable four-game sweep of Atlanta on Sunday. The Rockies now lead the Dodgers in the division, and sit a half game back of the D-Backs. Meanwhile, the Braves remain in a dogfight with the Phillies for the top spot in the NL East.

Marlins vs. Nationals

With the Phillies and Braves duking it out atop the division, the Nationals still can't climb out of third place. Seven games back of the division, Washington desperately needs series victories, and likely should have come away with three wins against the Marlins. Instead, they dropped two of three, and sit one game under .500. The Nats now have a 13 percent chance of making the playoffs, according to FanGraphs.

(Pictures courtesy: Getty Images)