Yankees dodge headache with Posada OK

The whole half inning made little sense.

It was the bottom of the seventh yesterday. The Yankees trailed 2-1. There was one out and a runner on first. Orioles skipper Buck Showalter brought in lefty Mark Hendrickson and manager Joe Girardi kept Lance Berkman in to hit, though Berkman is feeble against lefties.

Berkman struck out, then Girardi turned to lefty masher Marcus Thames, though waiting the extra spot in the order enabled Showalter to counter with a righty, Jim Johnson. Nevertheless, Thames singled to put runners at the corners. Thames represented the go-ahead run, yet Girardi did not pinch-run — and after the half inning he installed the defensively challenged Thames in left field.

BOX SCORE

But, by far, the strangest move came when Girardi did not pinch-hit for Francisco Cervelli with Jorge Posada against the righty Johnson.

Except, as it turned out, this was not a misstep by Girardi. At that moment, Posada was at New York-Presbyterian undergoing neurological tests because he was suffering from what Girardi described as “concussion symptoms.” At that moment, Posada could have been unavailable for a lot more than one key at-bat in early September.

Posada had not started, but no alarm bells were set off because it was a day game after a night game. But his no-show in a spot that hungered for an RBI man — not Cervelli — was glaring and led to questions.

Had such a scenario not transpired, sources told The Post, the Yankees were not planning to reveal Posada’s condition publicly. That is because their initial read was that the injury was not serious and the extra testing was just to allay all fears. That initial read proved correct. Posada returned to the clubhouse after the Yankees had defeated the Orioles 3-2 and told the teammates who remained that he was fine. Shortly thereafter, the club put out a statement saying the additional tests were negative.

Posada will fly with the Yankees to Texas today, a team official said, though he may not start for a day or two.

Still, this was a sigh-of-relief moment — as long as the diagnosis was correct; remember the Mets let Jason Bay play for two games in late July after suffering what they thought was whiplash, but turned out to be a concussion that likely has ended his season.

Posada’s receiving skills have diminished further. Nevertheless, the Yankees did not want to face October depending on a Cervelli/Chad Moeller catching tandem. No postseason opponent would spend more than a few seconds in a scouting meeting discussing Cervelli or Moeller. Posada, on the other hand, still can change a playoff game with one swing from either side of the plate. Plus, his experience guarantees that the moments will never be too big for him.

“You’re talking about a guy that’s playoff-tested, World Series-tested, September-down-the-stretch-tested, a switch-hitter in the middle of our lineup,” Girardi said. “It’s an impact [if Posada had been lost].”

It also would have added to a significant list of concerns for the AL East leaders. Most worrisome are that Posada’s pal, Derek Jeter, remains an out machine at the top of the lineup and the rotation is still CC Sabathia’s wing followed by a prayer. They certainly did not need to find out what life without Posada would look like.

The Yankees did not start Posada on A.J. Burnett’s postseason turns last year, and might match up Cervelli with Burnett this year. But after Posada took a foul ball off the mask Tuesday night, reported feeling, in Girardi’s words, “foggy” following that game and still suffering from headaches before yesterday’s action, the team suddenly had to contemplate not having him for any of the postseason this year.

It was a reminder how fragile a season can be even when, like the Yankees, you have the majors’ best record and a playoff spot all but guaranteed. One inadvertent foul tip can make you wonder if Francisco Cervelli is truly up to doing a lot more than batting with first and third and two outs on a Wednesday afternoon against the Orioles.

joel.sherman@nypost.com