For better or worse, the Mets pretty much stood pat with their lineup this offseason, the romance gone wrong with Carlos Correa notwithstanding.

But there was cosmetic surgery on the starting rotation that in retrospect and at this moment in time seems like malpractice.

A year ago, the rotation recorded the NL’s third-best ERA at 3.61 and compiled the third-most innings and third-most quality starts. This year’s rotation has spun off its axis, with the third-worst ERA at 5.03, the third-fewest innings and the fifth-fewest quality starts.

That goes a long way in explaining why 101-61 last season has become 33-38 this season following Sunday’s 8-7 defeat to the Cardinals at Citi Field, in which Carlos Carrasco was battered around for three-plus innings until taking leave of the situation with his team on the short end of it.

Glimmers of hope seem to be extinguished almost daily. The Mets had won two straight after defeating St. Louis on Friday. There was reason for some optimism. But two straight defeats followed.

One step forward, two steps back.

And by losing two out of three this weekend to the NL Central’s worst team, the Mets have now won just one of their past eight series (1-6-1) since completing a sweep over the Phillies on June 1 and only three of their past 16 series (3-11-2) beginning the final week of April.

They are on a treadmill to obscurity.

Chris Bassitt led the Mets in innings pitched last year. Taijuan Walker was second. Both were ushered into free agency and onto the open market. Jacob deGrom of course bid adieu. The Mets signed Justin Verlander. They signed Kodei Senga. They signed Jose Quintana.

They seemed set. Past is prelude the present, correct. Over the course of a season, it’s all about the back of the baseball card, right? Isn’t that the most popular adage in baseball?

But not apparently to manager Buck Showalter, who said the rotation’s difficulties have not necessarily been the biggest surprise of the season. Could have fooled everyone else.

“I know how hard pitching is, especially, and [expectations] are all based on the past,” he said. “It’s not today and it’s not tomorrow and it’s not this season of April, May and June.

“It didn’t mean that you’re going to accomplish something just because you’ve done it in the past. I don’t ever assume that and I know players and coaches don’t, either, because you know how little the past really means to it.”

Now, listen, I’m not equipped to engage in a debate about baseball with Showalter, but come again?

Why did the Mets sign Justin Verlander to a two-year, $86.667 million contract if not off his career past performance that featured a 2022 Cy Young season? Why did the Mets sign Max Scherzer last year to a three-year, $130 million deal if not for his past performance?

Again, there’s still a lot of runway in front of the Mets, in front of Scherzer, in front of Verlander, in front of Carrasco, and in front of Quintana, who had his second rehab work on Sunday in Port St. Lucie and could land in Queens around the All-Star break that begins on July 10.

“It can get real positive in a hurry if you can get consistency [with the rotation],” Showalter said. “But I don’t hang it around one phase of the game.

“Everyone is so quick to want to point out, stand up and say that this is, ‘It,’ I’ve identified, ‘It.’ It’s so much more than that. I try not to live in that world.”

The Mets were down 5-1 after two St. Louis turns at bat — the Mets’ first-inning ERA is 6.34 and Carrasco’s is 9.00 — but came back to 5-4 by the end of the second. Then it was 6-4 and 6-5. Then it was 7-5 that became 7-7 in the fifth on Tommy Pham’s two-run homer. That’s how it remained until Nolan Arenado put one in the left-field seats off Adam Ottavino with one gone in the ninth.

Sisyphus being pushed down the hill again.

The Mets don’t quit. They make errors, another two in this one, but they don’t quit. That might be enough if the team did not have great expectations.

Great expectations that were based on the back of the roster’s baseball cards.