MLB

Pinstripe plus

September has to be better than August because if it isn’t the Yankees could be out of the postseason for the second time in five years. Or forced to play a one-game, wild-card playoff to advance to the ALDS.

When July sweated into August the Yankees held a 5 1⁄2-game lead over the second-place Orioles despite ending the month on a four-game losing streak.

Thanks to a pedestrian 15-13 August ledger after last night’s 6-1 loss to the Orioles at Yankee Stadium, the Yankees’ edge over the Birds was shaved to two.

Now, with 25 of the final 31 games against AL East opponents — six with Baltimore; six with Tampa Bay, which is still 4 1⁄2 games back — the Yankees can’t afford another so-so month.

BOX SCORE

Here is a look back at August, a month that might have cost the Yankees a postseason spot:

MVP

With Alex Rodriguez missing the entire month and Mark Teixeira battling hand and leg problems, Derek Jeter and Nick Swisher carried the Yankees at the plate.

Jeter batted .350

(43-for-123) and hit six of his 14 homers in the month.

Swisher, who was inserted into the No. 2 spot behind Jeter on Aug. 8, hit .305 (33-for-108) with six homers and 22 RBIs.

LVP

Curtis Granderson and strikeouts haven’t been strangers across his career. However, Granderson started the month a career .264 hitter and batted .196 (19-for-97) with six homers and 20 RBIs. With 34 homers Granderson remained among the league leaders but a .270 on-base percentage for the month was 33 points below his career mark.

LOOKING AHEAD

Five months into the season, Buck Showalter has to be considered a strong candidate for AL Manager of the Year, and though the Orioles could falter in the final lap, it hasn’t happened yet.

The Yankees have 12 games remaining against with the Orioles and Rays, and how they do will decide if the Yankees win the East, are one of two wild-card participants or miss the postseason.

The Yankees expect to get Rodriguez back, but what will he look like? Hands are very tricky injuries for baseball players and Rodriguez didn’t do well when he returned from a thumb injury late last year.

The Yankees are hoping to have Andy Pettitte at some point, but it’s starting to look like a long shot.

YOU DON’T WANT TO BE JOE GIRARDI

When the Yankees’ lead was 10 games on July 18, questions about not making the postseason were being asked in other cities.

Now, having lost eight lengths off that cushion, there is a chance the Yankees will get shut out of the postseason.

Already facing an offseason filled with many question marks surrounding the free agency of Russell Martin, Swisher, Mariano Rivera, Pettitte and, likely, Rafael Soriano, and the possibility of signing Robinson Cano and Granderson to multi-year deals, the Yankees missing the playoffs or losing the wild-card game would put manager Joe Girardi’s job security in play. He is signed through the 2013 season.

On the flip side, winning the division and playing in the ALDS would mute all that talk.