MLB

Rivera’s early arrival could signal end of Yankees career

TAMPA ­— The chair was occupied, and — in its own way — that was perhaps the first clue it would not be for much longer.

When the clubhouse door opened to the media early yesterday morning, there was Mariano Rivera sitting at his locker. On the surface, so what? But there are Mo Rules in spring, and one is that he will not report on time.

No one around the Yankees cares. He is Mariano Rivera, and his history is he shows up in great shape, pinpointing pitches and needing six to eight innings in all to be ready for Opening Day. And this year, Rivera had cautioned general manager Brian Cashman at the Baseball Writers dinner in January he was going to be particularly late to spring training. So when Rivera was there yesterday on time, Cashman actually exclaimed, “He’s early!”

But my theory was the early arrival was about it being late in his career; if this is the last year, then Rivera wants to experience everything one final time, from pitchers and catchers to, he hopes, the Canyon of Heroes.

Rivera laughed when I told him my theory, saying I was trying too hard.

“You are fishing,” said the son of a Panamanian fisherman who defied the odds to become the greatest closer ever.

But it was hard to ignore we were having this conversation on a stroll from a back field where Rivera — also not per his custom — had spent about a half-hour signing autographs, a lone Yankee in a sea of fans.

Then, in two separate long interviews with reporters, Rivera hinted strongly at retirement without using the words. He explained, “I know now, but I just don’t want to tell you.”

He said his decision could not be changed by money or 2012 success. He said it was important he depart still performing at an elite level and if it were up to his kids he would not even have pitched last year.

He feels an even stronger pull toward family and church after being shaken by a winter throat cancer scare. He had polyps, but the procedure to remove them left Rivera unable to speak for a week. Healed now, he felt another strong pull — to honor the one year left on his contract and toward one more year of the joy he felt simply by putting his uniform on again yesterday.

At age 42 and in his 20th major league camp, Rivera compared himself the Energizer Bunny. He certainly looked as athletic and agile as anyone going through fielding drills, and fellow reliever Rafael Soriano declared, “We played catch today. He’s ready to go.”

Except “he is ready to go” has a different connotation now. Suddenly, the Yankees are facing their Day After Tomorrow.

“Really if I thought about replacing him that would have started 10 years ago,” Cashman said. “And it would have been a waste of energy. That day will come. I’m thankful it has not come yet.”

Someone else eventually will do his job, but Rivera — because of his poise, precision and durability — is basically irreplaceable. He arrives to this season, as usual, peerless and fearless, incomparable and inconceivable.

He has been a full-time reliever since 1996, for 16 seasons. If you break that span into four-year segments, his numbers are almost uniformly better from 2008-11, when he was 38-to-41, as in any other period — though in the other periods he was never less than brilliant.

In other words, as he heads toward the exit, Mariano Rivera might be getting better. He certainly is not worse. In his first four full seasons, from 1996-99, Rivera finished second in the majors in on-base percentage allowed and first in slugging (minimum 900 plate appearances). From 2008-11, he was first in on-base percentage and second in slugging.

And, of course, he has been better in the postseason than in even the best of his regular seasons.

As the 2012 campaign begins, he said, “My arm feels good,” and described himself as “having no doubts” that he will be himself — which is to say The Best.

“He probably can pitch until he is 75,” catcher Russell Martin marveled.

But Rivera doesn’t want that. All indications are this is it, and Rivera — in another sign of where he is heading — said he was going to savor every moment.

My advice to those who love the game is to do the same. Because once this ends, we will never see anything like Mariano Rivera again.

joel.sherman@nypost.com