Alex Rodriguez of the New York Yankees reacts after striking...

Alex Rodriguez of the New York Yankees reacts after striking out in the ninth inning against the Seattle Mariners at Yankee Stadium on Saturday, April 16, 2016. Credit: Jim McIsaac

The boos finally came Saturday in the ninth inning, when Alex Rodriguez whiffed badly on a Steve Cishek slider. It was the desperate swing of a slumping player, chasing hope as much as that sharp-breaking pitch.

Both eluded Rodriguez during the Yankees’ 3-2 loss to the Mariners. And because he is who he is, A-Rod usually shoulders most of the blame when his team’s offense malfunctions. Now is one of those times.

Rodriguez went 0-for-5 with three more strikeouts Saturday as his current dive deepened to 0-for-19 with eight Ks since the first-inning homer off the Tigers’ Mike Pelfrey on April 9. He is 3-for-30 and has a .100/.229/.200 slash line.

We know what you’re thinking. Rodriguez is 40, and his advanced age, along with the two hip surgeries, has caught up to him at last. He’s through.

It’s a fair assumption. After all, even a guy with 688 home runs is human.

But hold off on the cards and flowers. Two weeks into the season, we’d say that’s a tad premature. As for how Rodriguez feels about the age question, he insists he doesn’t.

“Look, I think those are things I can’t control,” he said. “I think my job is to come out and worry about the next at-bat. Not the last at-bat.”

That mental approach is the only way to survive in the majors for two decades, the armor necessary for such a humbling game. It’s also possible that Rodriguez does feel a twinge of doubt, as an older player nearing retirement, but would never reveal it.

For now, however, we’re still dealing with too small a sample size to bring the curtain down on A-Rod’s career. The Yankees’ lineup, almost from top to bottom, is underperforming at a ridiculous rate, and Rodriguez is the only forty-something of the bunch.

With Saturday’s loss, the Yankees are 3-for-46 (.065) with runners in scoring position in their last five games. It’s an epidemic of poor production throughout the roster, not merely A-Rod having a senior moment. And if this could be solely attributed to age, then how is David Ortiz — another DH only 114 days younger than Rodriguez — batting .333 (10-for-30) with three homers and a 1.244 OPS?

Because Ortiz is off to a great start and A-Rod isn’t. Sometimes the explanation really is just as simple as that.

“It’s perspective,” Rodriguez said. “If something like this happens in July or August, you don’t think too much of it. But you want to go out and do well. The two things you can control every day when you come to the park is your attitude and your effort. And I feel pretty good about both.”

One thing beyond A-Rod’s control, however, is the lineup card, and it’s not too early for Joe Girardi to reconsider Rodriguez in the No. 3 spot.

Clearly, he’s got to stay in the lineup and work his way out of the abyss. But that doesn’t have to take place in such a premium location, and sliding Rodriguez down a few slots seems as if it could be a no-lose option, especially with Carlos Beltran as a ready-made replacement at No. 3. Beltran, batting fifth, went 4-for-5 with a homer and two doubles on Saturday to improve his slash line to .351/.368/.649.

When asked about a potential switch, Girardi didn’t tip his hand, which was expected. Not his style. But he’s paying attention. The Yankees can’t buy a timely hit and their $20-million DH is doing zippo from the most critical link in that chain.

“The one thing you don’t want to get too caught up in is changing your lineup every day because you want some consistency,” Girardi said. “But obviously guys have to produce to stay in those spots to be consistent.”

As for what the manager might do, or when, Girardi said he hadn’t given it much thought during the 20-yard postgame walk from his office door to the media conference room. But Rodriguez not only failed to perform Saturday but looked feeble in the process. While that’s natural against someone like Felix Hernandez, getting punched out by lefty Vidal Nuño to end the sixth was a bit more alarming.

“I’ve played a lot of games and had a lot of ups and downs,” Rodriguez said. “You got to come to the park and grind through it.”

Right now, 40 isn’t the most troubling number for A-Rod. But unless a few of those others start improving, it could be before long.