Mets pitcher Jacob deGrom looks on from the dugout during...

Mets pitcher Jacob deGrom looks on from the dugout during an MLB game against the Brewers at Citi Field on June 16. Credit: Kathleen Malone-Van Dyke

One day, presumably in the very near future, Jacob deGrom starting a game for the Mets won’t be a hypothetical concept.

But for the past four months, you would’ve had better luck picking the Powerball numbers than figuring out the date. And it’s hard to nail down why that’s been the case.

Is it because the rehabilitation for a stress reaction injury to the shoulder blade can be an inexact science, compounded by deGrom’s tangled medical history? Or is there something else at work here, a complication that crept up, a reason for deGrom to pump the brakes, his own (opt-out) future a factor in this recovery?

In any event, deGrom took the next step Thursday by throwing a 60-pitch simulated game in Port St. Lucie, and the Mets said there where no issues with the previous muscle soreness around his shoulder.

All along, the Mets’ company line, as occasionally voiced by Buck Showalter, is that deGrom has hit every benchmark along the way, as scheduled. We’d counter that his return date was always a moving target — and deliberately so, thereby eliminating the need to use any scary words like “setback.”

That worked pretty well for a while, right up until Tuesday — the date tentatively listed as what possibly, maybe, perhaps would be deGrom’s final simulated game before rejoining the Mets’ rotation. But that didn’t happen.

Instead, right around the start of the All-Star Game, with the baseball world locked in on Clayton Kershaw’s first pitch to Shohei Ohtani, the Mets announced that deGrom “presented with mild muscle soreness around the shoulder” on Sunday and his sim game at the Port St. Lucie complex had been pushed back to Thursday “out of an abundance of caution.”

While that statement alone shouldn’t necessarily have set off sirens in Metsville — doesn’t everyone present with a sore muscle any given morning? —  it’s obviously different when we’re talking about deGrom, a two-time Cy Young winner who has the fan base hanging on his every tweak and twist. This is not to say the Mets and the Flushing Faithful have been held hostage by deGrom’s reclusive greatness going on 13 months now, because everyone has moved on to some degree — the team entered the break with a 2 1/2-game lead in the NL East and the second-best winning percentage (.624) in franchise history for a first half.

But yeah, it still feels a little like that. Because you can’t really talk about the Mets’ projections for the second half, or handicap their World Series chances without prominently mentioning “when deGrom gets back.” As much as the players themselves are conditioned to put aside their missing teammates to focus on the task at hand, it’s not so easy to shrug off deGrom’s absence. On the 1-to-10 scale of elite pitchers, deGrom is an 11. Even David Peterson, who has been solid filling in for deGrom and is likely headed back to Syracuse when (if?) he does return, can’t help but echo the clubhouse sentiment.

“We all want Jake back,” Peterson said. “We all want him healthy. That’s the most important thing. We want him to be productive and we want him to be Jake, the Jake that we love and know.”

But does that Jake still exist? It’s a fair question. I believed that the Mets were in store for an even better version of deGrom this year when he showed up for spring training. Rested, and looking visibly stronger, his wiry build more ripped than before, deGrom didn’t even make it through March before suffering the stress reaction in his shoulder. That upped his total to 11 different ailments over the span of only 21 months, including three stints on the IL.

If deGrom snapped so quickly in the Grapefruit League after not throwing a pitch in the majors since July 7 of the previous season, what does that suggest for when he makes it back this time? Would any amount of rest and recovery truly be sufficient going forward for this 34-year-old ace?

Maybe deGrom was intent on squashing that skepticism in his first rehab start for Class A St. Lucie on July 3, when he fired seven pitches at 100 mph or more, maxing out at 101. The Mets admittedly were a little spooked by his extreme velocity from the jump, but chalked it up to deGrom just doing what he does. Showalter, nor anyone else, dared to suggest deGrom could possibly start off a little less aggressively.

It’s a moot point now. DeGrom has logged three rehab starts — hitting 100 mph in all of them — and theoretically was only one sim game away from rejoining the Mets for this upcoming homestand, with a chance to face the Yankees either Tuesday or Wednesday at Citi Field. That would seem to be the rough outline anyway.

From there, who knows? Any excitement over deGrom’s return has to be tempered by the Mets' constant monitoring of him, like some helicopter parent, and the rest of us acknowledging that his status — even when supposedly healthy — should always be listed as day-to-day.