UNPRECEDENTED. Pretty near impossible.

Mark Jackson, the ex-Knick and St. John’s floor boss, has, with only a few telecasts’ prior experience, slid so comfortably into the role of Nets YES courtside analyst that he threatens to become among the sharpest, smoothest and most compelling listens to ever follow the bouncing ball.

Jackson – a rookie, for crying out loud – has aced the ultimate test. He’s at least as good as the game he’s working. You can tell. Several minutes after tuning in, it isn’t all that important who’s playing and what the score is. That’s because there’s a guy working the game and he’s talking calm, clear, applicable basketball sense.

And we’re loving it.

And he’s not throwing a bunch of numbers at you. And no neo-hip attitude. He even knows that silence often sounds smarter than non sense, that it’s not necessary to speak after every possession. Is that allowed? Who knew? Who cares? It’s Brilliant!

What a concept.

“Knowing when not to talk,” Jackson told us, “comes from being mar ried.”

Beyond that, Jackson, 40, is so good he seems surprised by the accusation.

“I guess it’s a combination of three things. I’ve been positioned next to two pros, Marv Albert and Ian Eagle. They make it easy. I was hand-picked by Marv. He pushed to get me. That’s a high form of flattery.

“Next, I was a point guard and I still have a point guard’s mentality. I’m conditioned to see the entire game, a lot of things at once.

“And, I’m a student of the game; I watch a lot of games.”

Jackson’s also a natural and concise raconteur, making him particularly valuable to advertisers as he can hold an audience during garbage time. Wednesday night, as the Nets were finishing off the Sixers in Philadelphia, Jackson told this one:

He was with the Pacers, in a playoff series against the Sixers. Looking to kill time between games in Philly, he went shopping, only to find that the store he wanted to enter was closed. Odd, it was during business hours.

He looked through a window to see people in the back. He tapped on the window. The door was opened and he was invited in be cause the sole shopper in the store recog nized him and gave him the OK. “It was Allen Iverson. They closed the entire store so that Allen Iverson could shop there.”

And he’s relaxed, breezy, easy. When a sky-high Vince Carter bomb was selected as the “Play of the Game,” Jackson began to sing, “Somewhere, over the rainbow . . .” Brief, corny, perfect.

Good stuff, start to finish, none of it forced. Unlike those who will enlighten us with, “The Buzzards have to begin converting their field goals in the final stanza in order to rally from this 14-point deficit,” – ugh! – Jackson’s the guy you want to find yourself seated next to at a game.

“I don’t want to sound like a guy doing an imitation of a sportscaster,” he said. “I just try to act as if we’re on the couch, watching the game, talking to the fellas.” What a concept!

*

The moment everyone ceased jumping to easy, simplistic conclusions – “another drunken, abusive fan!” – is when facts began to emerge relevant to that Antonio Davis hassle in Chicago. It should have been the other way: a jump to the facts, followed by conclusions.

Post thoroughbred writer Ed Fountaine touts just-retired jockey Jerry Bailey as TV’s next, great racing analyst, one able and eager to clearly and frankly speak his mind. . . . TNT’s NBA studio show is becoming so crowded and noisy that it’s beginning to look and sound like “The View.”

The replay rule did not become a bad rule last week in Indianapolis. It was always a bad rule, one rarely used as intended and one that’s now regularly used to issue worth-a-shot, desperate challenges because it has the ability to change good calls into bad ones. Football’s a game. It grew as a game and became cherished as a game, not as an inexact exact science.

Funny how the NFL’s networks, in their lead-ins to playoff games, present epic movie-inspired dramatics – over-written, over-narrated, over-scored come-ons. Who are they for? We’re already watching, no? Or do they think that people who just watched the pre-game show would change the station unless they were encouraged to watch the game that follows?

*

Wednesday, Chris Russo said that he was bothered by historical inaccuracies in “Glory Road.” To that, Mike Francesa said he was similarly bothered by historical inaccuracies in “Seabiscuit,” including one that served as “the arch” of the movie.

Strange, Francesa and Russo had absolutely no problem ignoring the historical inaccuracies in Billy Crystal‘s “61*.” And Crystal even declared the movie to be historically immaculate.

Francesa and Russo even dismissed critiques that found “the arch” of 61* – the impossible depiction of Yankee Stadium erupting in hatred for Roger Maris after he hit a game-winning homer in the midst of the pennant race – to be absurdly inaccurate.

Then again, Crystal was with them at the time. Francesa and Russo rarely say the same thing to guests that, before and after, they say about them.

phil.mushnick@nypost.com