There is the baseball season you imagine, and the one we actually get.

We imagined Derek Jeter coming back to defy age again, to be, you know, Derek Jeter. In recent days, we began to imagine if a Mets lineup could have both John Buck and Travis d’Arnaud.

But the season — reality — has other plans. Now we ask a question that seemed unimaginable even 72 hours ago: Who will play first in 2013, Jeter or Alex Rodriguez?

Now we wonder if d’Arnaud is injury prone and is even going to see any kind of significant major league run in 2013.

The season — the reality — got cruel for both New York teams Thursday, and for the lower left legs of Jeter and d’Arnaud. Brian Cashman announced that a crack was found in Jeter’s ankle, near where he had surgery to repair a fracture. The Mets announced d’Arnaud fractured his foot.

Jeter is not due back until after the All-Star break and d’Arnaud is expected to be out anywhere from one to two months. But recurring leg injuries for 39-in-June shortstops and catchers of any age are not particularly obedient to timetables.

After all, Jeter pledged to be back Opening Day, then the clock was reset for May 1 and as recently as two days ago Joe Girardi described the shortstop’s reduced rehab workload as not a setback. I remember the Mets said the same early in spring training about Johan Santana stopping his throwing program. No setback.

We can be sure of this, though — both New York baseball teams suffered significant setbacks yesterday. Both had major plans shattered.

Maybe we all had been deluding ourselves about Jeter. His pain tolerance and inner drive are such we assumed he could defy age and wear and injury because he has done it so often throughout his career. But that fracture he suffered in Game 1 of the ALCS last October was devastating. And he does not have a desk job. He is a shortstop who needs to start and stop quickly over and over, day after day, month after month.

The history of the sport shows not many have played shortstop at anywhere near a high level at his age. At 38, he disregarded that history, led the majors in hits in 2012, played rather brilliantly. Now?

No one should bet against him. Mariano Rivera has come back from a devastating injury and looks like Mariano Rivera, and the two are cut from similar self-confident, hard-working, defiant granite. But losing at least a half season now means we can suspend — if not outright dismiss — talk of Jeter chasing 4,000 hits and Pete Rose. We also are going to get a more definitive answer whether Eduardo Nunez is a major league shortstop.

And we now have to accept the possibility Jeter will never again be an everyday even above-average shortstop. Again, the position demands a quick-twitch skill that recurrent injuries to that left ankle may not allow.

As for d’Arnaud, remember the Mets sent him to the minors because they said he needed the game action, having been robbed of that due to back and knee injuries over the past few years. Now, a foul ball has broken a foot. Back and leg injuries are as problematic for a catcher of any age as, say, an ankle injury is for a shortstop.

The Mets were giddy so far this year that their supplemental piece to their big trade, Buck, was outperforming R.A. Dickey. But no one was kidding himself. That deal from the Mets’ end is going to be judged by whether d’Arnaud honors the projections as a high-end offensive catcher.

Of course that is still possible. But let us also remember the ticking clock does not stop. D’Arnaud is no baby. He is 24 — six months older than Jason Heyward. The Mets’ best-laid plans had D’Arnaud and Zack Wheeler breaking in this year and being part of a serial contending cornerstone for next season.

So much for time tables. So much for the seasons you imagine. This really does follow no script. And the rewrite of plans yesterday was particularly unkind for New York baseball. A couple of left feet broke down and took a piece of the season with them.