HOUSTON — As sad as it might have been to watch CC Sabathia leave a playing field for the very last time as an active player, his shoulder hanging limp against his body late at Yankee Stadium late Thursday night, there was also something quite noble about the picture, too, something Sabathia himself referenced Friday afternoon.

“I think it’s just kind of fitting,” Sabathia said. “I threw until I couldn’t anymore.”

It felt like a perfect juxtaposition against what happened late last week to two of the brightest lights in all of sports, both breathtakingly young, both with a boundless road of possibility stretched out in front of them.

First, on Thursday night, Patrick Mahomes — already nursing a bad ankle — was asked by coach Andy Reid to attempt a quarterback sneak on fourth-and-inches late in the first half of the Kansas City Chiefs’ game at Denver, deep in Broncos’ territory.

Mahomes got the first down, but he also got something else for his troubles: a dislocated kneecap, delivered at the bottom of the pile. Mahomes’ reaction was visceral and it was hard to watch. He was racked with pain. Around him, teammates and opponents alike took knees and bowed their heads in prayer, fearful that they’d just seen a calamitous event.

It turns out, Mahomes may well miss only a couple of weeks, thanks to some quick service by the Kansas City training staff, but the sight of him walking off the field without a helmet — even if it was just a slow, halting gait and not a limp — was a jolt for the whole sport because Mahomes, all of 24 years old, is perhaps the brightest young player in the whole league, a generational and a transformational talent. Even if his absence is just for two or three weeks, it’s a gaping hole in the NFL landscape.

A day later came the announcement Zion Williamson will miss the first few weeks of the NBA’s regular season thanks to his own bum knee, injured last Sunday in the New Orleans Pelicans’ preseason game against the San Antonio Spurs. The Williamson announcement, like Mahomes’, was actually good news, since the Pelicans feared the diagnosis could be much worse.

Really, all it cost Williamson — who won’t even turn 20 until next July — was the opportunity to reunite with college running mate RJ Barrett when the Pelicans played the Knicks in an exhibition Friday at the Garden. As with Mahomes, it was a scare more than anything else, and the news could have been much, much worse.

But it was another reminder just how fleeting this can all be, even for the kids, and a reminder to appreciate those who do endure the grind of an athletic career and live to tell about it with a laugh and a smile. Sabathia, 39, spent the past few years of his career battling a variety of ailments, but he actually got to the end of his career — a full one, long enough to surpass the 250-win and 3,000-strikeout benchmarks that will probably be fruitless pursuits for most of the pitchers who came or come after him.

And when you consider the other exciting young player on the American landscape, Fernando Tatis Jr. of the San Diego Padres, also lost most of his rookie season to injury — as well as a chance to give the Mets’ Pete Alonso a genuine fight for the NL’s Rookie of the Year award — it only emphasizes how brittle it all is.

When Tatis was shot down for good in August with a back injury, he was hitting .317 with 13 doubles, 22 homers and 53 RBIs in 84 games, and he was playing a spectacular brand of shortstop. Like Williamson in the NBA and Mahomes in the NFL, he was exactly the kind of rare talent his league craves — young, appealing, with a genuine flair that sets him apart from almost all of his peers.

Sabathia on Friday joked about being “an old man,” but he was given the greatest gift an athlete can ever hope for: longevity. It is something we can only hope for Mahomes, Williamson and Tatis, three stars blazing across the sky who must be blessed with good health to feel as good about themselves, 15 years from now, as Sabathia does today. Even if his shoulder aches.

Vac’s Whacks

So for the foreseeable future, rival teams in our town have Judge vs. Alonso to argue about, and Darnold vs. Jones, and Hughes vs. Kakko and Durant vs. … um, yeah, check back on that last one.

At this point, wouldn’t it be more newsworthy to identify the people who aren’t interviewing to be the Mets’ next manager?

You won’t read a more fascinating new book than “The Life and Afterlife of Harry Houdini,” written by my old friend Joe Posnanski, which will be released this Tuesday. You don’t have to be an aficionado of magic to enjoy it, simply a lover of good writing and expert storytelling.

Good for the Nationals, who should be an inspiration for all baseball teams that sometimes it’s best to hold ’em, rather than fold ’em, even at 19-31.

Whack Back at Vac

Steven Schafler: It seems the only player Adam Ottavino can strike out at this point is a deceased Babe Ruth.

Rich Nutie: I believe I have the answer to Gary Sanchez’s playoff slump. Let Adam Ottavino pitch to him.

Vac: Now THAT’S savage!

Richard Siegelman: I can’t read about Patrick Day’s coma, death and life without tearing up, but I have to amend fight promoter Lou DiBella’s touching “It becomes very difficult to justify the dangers of boxing at a time like this” to, “It becomes impossible to justify …”

Vac: As someone who spent many a glorious night watching the fights on TV with my dad, I wish I could argue this point. But it’s becoming harder and harder.

@mostrowski52: Years ago, Bill James recommended that inexperienced managers play thousands of games of Strat-O-Matic to get the feel of making lineups, double-switches and so on. By the way, that makes me highly qualified to take over the Mets job.

@MikeVacc: Add this to the list of things someone should have suggested to Mickey Callaway.

James Yu: The next Mets manager needs to be: 1) a first-timer; 2) eager to not only listen to but also obey the GM’s demands; and 3) low paid (around $1 million). The perfect choice is Brodie Van Wagenen.

Vac: Hard to follow a mic-drop like that one right there.