Look at the bright side, Yankees, at least the sewage didn’t back up Saturday night at O.co Coliseum. Everything went down the drain for the Yankees, who are going to have to come up with one more hitter on the trade front. The O, by the way, stands for Obsolete. On Friday night, Mark Texieira sat in front of his locker here and said these fateful words: “Every win is a big win for us. We don’t have a huge margin for error.’’ That margin of error became that much thinner Saturday night when Teixeira was a late scratch with rib cage tightness before the Yankees’ miserable 5-1 loss to the Athletics. The defeat snapped the Yankees win streak at four games. Teixeira said he did not believe the injury was the always frightening oblique, and said it was a muscle that spasmed in his “mid-back, below the left shoulder. “Hopefully,’’ added a frustrated Teixeira, “it’s only a one-day thing.’’ The Yankees have only so much depth. At first base, they are really thin. That’s why it would have been wise, as pointed out in this space weeks ago, if the Yankees had gone out and signed Kendrys Morales. The Yankees didn’t go there. The Twins got Morales and the Yankees have little depth at first, where Teixeira is playing with a surgically repaired right wrist, and also missed time earlier this season with hamstring issues. Then, in the bottom of the fourth inning it got really weird. A bank of lights in left field, right above Reggie Jackson’s retired No. 9, never came on and, just before Jed Lowrie came to the plate in that fourth, the game was halted for 38 minutes.