As days go on the 2023 baseball calendar, Sunday was a good one for the Yankees.

Jonathan Loaisiga, who might be the Yankees’ best reliever, threw in a simulated game against Aaron Judge, who is Aaron Judge. Both appeared on the trajectory to return soon, as did Nestor Cortes, who was at Double-A making his first rehab start.

In the actual major league game, the Yankees completed a three-game sweep of the Royals, with Luis Severino mostly looking good for a second straight start and DJ LeMahieu, Anthony Rizzo and Giancarlo Stanton hitting all weekend like there might still be life in the old fellas.

It was a giddy pinstripe day. The kind to suggest that the Yankees are real contenders and that their owner and baseball operations department should be doing all that is necessary to upgrade the product between now and Tuesday’s 6 p.m. trade deadline.

Or was it a mirage?

The Royals, after all, look like something Double-A dragged in. They completed the weekend on pace to finish 46-116. The only positive thing to say is at least they are not the A’s, who were on pace to go 44-118.

The Yankees were 18-22 and had been outscored 181-157 since Judge went out of the lineup June 4 with a right big toe injury. But it is worse than that. They are 5-1 against the Royals and A’s and 13-21 against all other competitors. Yes, every team is playing every other team this year and you better beat up on the bad ones. But it is just how terrible the Yankees have looked against the others.

Their slash line in the six games against the weak sisters was .276/.351/.492, while averaging 6.67 runs per game and hitting a homer every 18.1 at-bats. In the other 34 games, the slash line was .211/.282/.360, while averaging 3.44 runs and hitting a homer every 30.4 at-bats.

Would the return of Judge — in whatever version that would be — plus a trade (or two) to address the offense really change these Yankees enough? It is why the Subway Series had importance beyond the usual turf war aspects. Both New York clubs were trying to address how to handle the deadline — buyer, seller, neither or both.

If things spun horribly this week, what would the Yankees even have to sell? The only time they did so with fervor in a half-century of Steinbrenner ownership was 2016, when notably they dealt Aroldis Chapman and Andrew Miller. The only remnant of those deals is Gleyber Torres, who the Yankees could in theory move before his walk year and insert Oswald Peraza at second the rest of the season to see how he performs. But second base is not a position that often fetches much in the market, especially when the player will cost $15 million-ish next year. The Yanks could follow the Chapman/Miller model and move Clay Holmes before his walk year and Wandy Peralta in his walk year. Holmes, in particular, would be a desirable piece. Harrison Bader in his walk year? Would a team take a flier on Severino in his walk year believing they will get the best of him for a couple of months?

More than likely, though, the Yankees will buy. But to what level? It would be motivating if the Yanks saw Carlos Rodon finally pitch well Wednesday against the Mets while continuing to hear positive updates on Judge, as they did when he played five simulated innings Tuesday. It is possible that Judge will play this weekend at Camden Yards — and that Loaisiga and then Cortes are not that far behind.

But does any of that whitewash how listless this club has looked, particularly during Judge’s absence?

The Yankees signed Rodon for six years at $162 million to give a 1-2 punch with Gerrit Cole against the Astros in October. Besides that the Yankees fail regularly in the postseason against Houston because their offense lacks batting average and diversity and gets shut down, there was the hubris to just assume another showdown with Houston. Which brings us to a toughness issue.

The Astros lost their best hitter, Yordan Alvarez, on June 9 when he was leading the majors with 55 RBIs. And Houston has had far worse starting pitching injuries than the Yankees. Yet, their Alvarez-less offense remained more than competent with a .755 OPS and 5.1 runs per game as they went 21-17 (2-1 against Oakland) to move from five out in the AL West to two out.

The Yankees have a few more days to demonstrate similar pluck and performance to convince the bosses it is worth investing further in this team. They need to show they can be royal pains against more than Kansas City and Oakland.