Willie Mays celebrates his 90th birthday on Thursday. He is the oldest living Hall of Famer now. But he is so much more than that.

Willie Mays is the greatest all-around player who ever lived, whose legendary career started at the Polo Grounds with the New York Giants in 1951. It means that for so many lifelong fans, he is the greatest player they never really saw. Even for the ones who did see him at his best, in the 1950s and ’60s, in New York and San Francisco, they go mostly on memories now, ones that No. 24 burned into their imagination forever.

There was never a “Last Dance” documentary for the dazzling and complete player known as the “Say Hey Kid.” It doesn’t change who he was and what he could do on a ballfield, which is to say everything. Tim McCarver, who played against Willie Mays, who was a catcher and so often had Mays standing right there in front of him in the batter’s box, was talking about Mays on Monday.

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“As his opponent,” Tim said, “you had to make sure you didn’t fall under his spell. Because that was the trap you could fall into being on the same field with him. You could be spellbound at the things he could do and the way he could do them.”

I mentioned to Tim that if you ever did see Willie Mays on a ballfield, in the time before you could watch a highlight reel on him and everybody else on television every day, you almost feel an obligation to pass on what you saw.

“I’ve always thought of it as a responsibility,” McCarver said. “There’s a reason why my old [Cardinals] manager, Johnny Keane, called him ‘the magic man.’”

And then McCarver was talking about how when his Cardinals of the 1960s, a historic team that played three seven-game World Series in five years and won two of them, would be getting ready to play the Giants in a regular-season series, Keane would tell his outfielders that unless it was the ninth inning of a close game, not to try to throw out Mays if he was on the bases and trying to score.

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“Johnny would say, ‘You’re not going to throw out the magic man,’” McCarver said, laughing. “Johnny would talk about how Willie would fool you into thinking you could get him at the plate, how he wanted you to try. But you wouldn’t. And all that would happen was that the guy who hit the ball would move up a base. Johnny was convinced that Willie would always run just hard enough to make it close.”

The late Hank Aaron -- who was Mays’ contemporary and from whom Mays would sometimes borrow a bat if he was in a slump and the Giants happened to be playing the Braves -- ended up being the one to break what was Babe Ruth’s all-time home run record of 714. But it so easily could have been Mays, who ended up with 660 home runs, who could have done it if he hadn’t lost nearly two full years of his career to military service as a kid, if he hadn’t spent so much of his career in the cold and wind of San Francisco’s Candlestick Park.

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He could hit and hit for power and run the bases like a streak of light and make the kind of forever catch he made in 1954 in the World Series against Vic Wertz of the Indians, nearly running out of the Polo Grounds to track down the ball in deep center and then wheeling, almost in the same instant, to throw the ball back to the infield. It was an old Dodgers executive named Fresco Thompson who once said that “Willie Mays’ glove is where triples go to die.”

There was, in Mays’ baseball persona, an elusive “it” factor that some athletes have and some do not, a quality that an old Boston columnist named George Frazier called “duende.” Michael Jordan had it. Mays had it. There was a time in America, when Mays was at his very best, that the highest compliment you could pay to any athlete in any sport was to say he had at least some Willie Mays in him.

The kid who started out with the Birmingham Black Barons knocked in 100 runs ten times in the big leagues. He hit more than 50 home runs in a season twice. He left the game with a lifetime batting average of .302. Only once in his career did he ever strike out more than 100 times in a season, and it happened to be the year he turned 40 with the Giants. There have been other center fielders to come along with otherworldly talent, but none of them have captured the imagination and transcended like Mays. Perhaps none ever will.

Mays came to Spring Training to do some coaching with the Mets after he retired, and one day at the batting cage I asked if he had any regrets. This was not so long after he had come home to New York to finish his career, and he would even end up in one more World Series.

“I’m just sorry that when I did come back to New York, I wasn’t the ballplayer I was when I left,” Willie Mays said.

You had to see him, the player Johnny Keane once called the magic man, someone who was a giant in all ways. His 90th is Thursday. It will feel like a baseball holiday. Happy birthday to him.