Here’s the thing about predicting trades in real time:

It’s like the way the late William Goldman once so perfectly described Hollywood: “Nobody knows anything.” We think we know. Fans do. Agents do. Sportswriters do. Talk radio does. We think we can spot a heist a mile away. But we can’t. Not every time.

You may recall a column I wrote a few days ago that tore open the anxiety closets of Mets fans everywhere, detailing some of the worst trades in franchise history. But here’s the thing: In the moment, when they happened, most people thought the Mets had done wisely in both 1969 and 1971 when they traded away Amos Otis and Nolan Ryan — 13 All-Star Game appearances between them — for Joe Foy (from Kansas City) and Jim Fregosi (from the Angels).

David Wright helped make this phenomenon go away, but the Mets searched for years — for decades — to find a reliable everyday third baseman. It was that obsession that made them pine for Foy and moon over Fregosi. And in the moment it seemed the Mets had done well — Otis never responded to Gil Hodges (who was certain to be in charge for a decade or more), and Ryan could never keep his blister-infested fingers out of Gus Mauch’s pickle jar.

And … well. That isn’t how either trade is remembered now.

Even trades that work out well for the Mets — Keith Hernandez-for-Neil Allen-and-Rick Ownbey — aren’t always what they seem. Yes, there was excitement when Frank Cashen pulled off that deal June 15, 1983, but there were also plenty of red flags: Allen was believed to be on the verge of stardom. Hernandez had been an MVP but was known to have his off-field demons and if Whitey Herzog didn’t want him on his team … well, what did that say?

The fact is, the overwhelming number of trades aren’t Brock-for-Broglio. Some trades look like steals up front but over time look more and more balanced (which is, after all, what a good trade is supposed to do). In truth, the very best trades should elicit the kind of debate

this Mets-Mariners trade

has: Is Robinson Cano worth it? Is he still productive? Did the Mets give up too many prospects, not get enough cash? Does Edwin Diaz make all the rest of it secondary noise?

We can shout now, and we can feel like we’re right.

But we won’t know. Not after a month. Not after a year. Maybe not until five or six years are past.

And even then …

This has always been one of my favorites:

Many Mets fans jumped at a big omission from my column the other day: when they traded Rusty Staub to the Tigers for an all-but-finished Mickey Lolich. One reader, Lou Ventura, could even cite the date of the trade — Dec. 12, 1975 — instantly, as a date that will live in Mets infamy. And yes, that trade was crushing for the Mets. Lolich was 8-13 in his only year as a Met, and his physique made David Wells’ look like Kent Tekulve; Rusty was an All-Star in Detroit and finished fifth in the MVP vote in 1978 when he drove in 121 runs.

But I ask you:

As popular as Rusty was as a Met (and it was earned; not only was he a key cog in the drive to the ’73 pennant, but his charity work will forever be remembered and his good will forever revered), the Mets got 3 ½ years of Rusty’s prime (he missed 96 games in ’72 with a broken hand) in exchange for all but 184 games of Ken Singleton’s decidedly borderline Hall of Fame career (his lifetime OPS was .824; Rusty’s was .793, and as a Met it was .778).

Couldn’t that be considered a steal, too?

Maybe, maybe not. The fact is, it’s a definitely a point of conversation. Which, at their base, is what every trade should be. Like this one.

Let’s just say that the NFL’s investigation of Kareem Hunt will probably never be ripped from the headlines for an episode of “Law & Order” — unless they want to make the cops look like bumbling buffoons.

I threw this out on Twitter the other day, and do so again: This soccer neophyte needs guidance on how it possibly makes sense that the Red Bulls worked all year for home-field (er, home-pitch) advantage … yet when they took the pitch Thursday they were already hopelessly down 3-0? Can’t MLS either do one-game survive-and-advance like the NFL or a best-of-three? Help!

If you haven’t read Peter Botte’s remarkable story commemorating the 40th anniversary of “The White Shadow” in Tuesday’s Post, two suggestions: 1. Read it immediately; 2. Cue up Hulu, where all the episodes are stored (yes, even Season 3, which we can all do without). Go hang with Cool, Thorpe, Salami and the crew for a few hours. You’ll be glad you did.

Somehow it has been 31 years since “Season on the Brink,” and somehow the great John Feinstein continues to set a gold standard for sports books, this time with “Quarterback: Inside the Most Important Position in the National Football League.” Also worth your time: “Guts and Genius,” by Bob Glauber, telling the dueling stories of Bill Walsh, Bill Parcells and Joe Gibbs during the 1980s.

Joseph Wilk: You forgot one the Mets won: Ed Hearn-for-David Cone!

Vac: They do tend to fall between the cracks, the good ones, don’t they?

Steve Eiger: As a 69-year-old lifetime Mets fan, I remember all these blunders. Thanks for including the Amos Otis-for-Joe Foy deal, which most people seem to not recollect.

Vac: It’s like a play on the old saying: Mets fans have forgotten more bad deals than most other fans remember.

@drschnip: Pessimist: Cano is the new Robbie Alomar. Optimist: Cano is the new Carlos Baerga!

@MikeVacc: #MetsTwitter has been an awful lot of fun this week!

Marc Aronin: If you’re from New York City, you don’t get — maybe don’t even want to get — why the Islanders returning home to Long Island this weekend matters. Why despite losing John Tavares, this is as big a victory for the franchise and fans as they’ve had in years.

@Vac: In a time of so much bad, the old hockey team returning to the new barn is a nice ray of sunshine