I will never be able to prove it. Not without a time machine or access to parallel universes. But I will always believe this Mets season would have gone dramatically — emphasis on dramatically — better had Edwin Diaz never been hurt.

It is not just about the closer’s pitching dominance or how he lined up other relievers in more fitting or comfortable spots. In 2022, Diaz evolved into the backbone of how the Mets played, and thus where they gained confidence. He shortened games. Opposing teams had, at most, 24 outs to get the lead or else the game would be over. — and they knew it. More importantly, the Mets knew it and were elevated by it, even on days when Diaz did not pitch.

Would it have persisted this year? Who knows? Maybe Diaz would have blown his first two saves and fit into the 2023 Mets narrative — with key players considerably worse than in 2022. But I think once he crumbled during that celebration at the World Baseball Classic with a torn right patellar tendon, it cost the Mets more than his 60 innings.

That is why how the Mets handle Diaz now is so vital. He is signed for four more years, and whether he reaches a major league mound before the end of the 2023 season has to be about one thing: having him physically and mentally ready for spring training.

Of course, that does not come with a script. Would two or three late-season MLB outings, for example, ease Diaz’s mind going into the offseason and allow him to show up for 2024 without concerns about how his knee will hold up? Maybe. But it is secondary to the Mets, who have insisted the priority is the soundness of his knee — even if they had been in contention, which they are not.

So they are proceeding more slowly than normal because only a handful of players — such as Zach Eflin, Garrett Richards and Matt Strahm — have incurred such a rare baseball injury. There is no clear roadmap as there is for rehab from, say, Tommy John surgery. So the Mets are being extra cautious — and the schedule is running out.

So the chance that Diaz pitches in the majors this season is less than 50/50. Still, he has rehabbed well from all indicators — progressing to playing catch off the mound, throwing to a non-squatting catcher. Bullpens and live batting practice would be the next steps. But will it go further? Minor league rehab? Major league games?

The Mets publicly are noncommittal. But, again, they also are non-contenders. They are not feeling external pressure to let Diaz pitch. What of teams still in the race with players who have yet to play a single inning this season, but still might?

The one-year anniversary of Walker Buehler’s second Tommy John surgery was Wednesday. The common practice now is to take more rehab time, as much as 18 months. But the hypercompetitive Buehler made returning this year a goal and already is throwing simulated games. The next step is a rehab assignment with the aim to try to be a hybrid three-or-so-innings pitcher for the playoffs. Buehler has a 2.94 ERA in 15 career playoff starts.

But the Dodgers have to be careful. Julio Urias and Clayton Kershaw are going to be free agents. Lance Lynn has an $18 million 2024 option that the Dodgers could pick up, considering how well he has pitched since they obtained him from the White Sox. Dustin May, who had elbow surgery in July, is out until at least the second half of next year. Tony Gonsolin is finishing this season injured. Youngsters, such as Michael Grove, Ryan Pepiot, Emmet Sheehan and Gavin Stone, offer depth, and after all the talk tying the Dodgers to Shohei Ohtani, there is a strong likelihood he won’t pitch next season. Still, the Dodgers cannot blow out Buehler this season, since he will be key to the 2024 rotation in his walk year.

Blake Treinen (shoulder), who underwent shoulder surgery in November, has begun an injury rehab and could make it back to the bullpen.

In 2016, Kyle Schwarber, then with the Cubs, tore his left ACL in the second game of the season and was expected to miss the whole year. While the NLCS was ongoing, he played in the Arizona Fall League and was activated for the World Series — an inspiration and a useful hitter toward the Cubs’ championship.

Rhys Hoskins tore his left ACL in a spring training game March 23, and the expectation was that he would miss the season. But he has progressed to running two out of every three days and doing some hitting off a tee. He has a ways to go and — like Schwarber — might need the Phillies not only to make the playoffs, but also to advance a bit, if he is going to have a shot.

Would you believe Houston had 348 fewer lefty plate appearances this season than the runner-up Yankees? It is easy to miss because the brilliant duo of Yordan Alvarez and Kyle Tucker had taken 880 of the 979 lefty plate appearances for the Astros, as opposed to, say, the Yankees’ Jake Bauers and Billy McKinney.

Michael Brantley last played on June 26, 2022, had shoulder surgery last August and missed out on Houston’s World Series run. He was re-signed and looked nearly back when a rehab assignment was shut down in April so he could build further strength. He played back-to-back games for the first time in his rehab Monday and Tuesday, and is expected to do so again over the weekend. If he can make it back, Brantley would bring lefty diversity, lineup depth and a professional bat to Houston’s attempts to repeat.

Like Hoskins, Brantley will be a free agent after the season, so a successful return would help his viability in the market.

John Means, who had Tommy John surgery, hasn’t pitched in MLB since April 13, 2022. He has made three Double-A starts and graduated to Triple-A on Friday. He is perhaps one more rehab start from rejoining the rotation as the Orioles try to secure their first playoff spot since 2016 and first division title since 2014. Means will be a free agent after next season, so he could also put minds at ease as Baltimore thinks about its 2024 rotation.

Chad Green last pitched for the Yankees on May 19, 2022, had Tommy John surgery two weeks later and signed a multi-permutation contract with the Blue Jays that could max out with a three-year, $27 million extension beginning in 2024. He has been rehabbing in the minor leagues and appears on the doorstep of activation. He can help the wild-card-chasing Blue Jays and his own financial possibilities with a strong few weeks.

The word of caution is that there is often anticipation for players who have been out of sight, if not out of mind. But getting up to MLB speed so far into the season is difficult. The Yankees envisioned all of last season that Zack Britton would return after Tommy John surgery to help with the bullpen. He came back in late September and had three terrible outings. No rehab or rehab return will be identical. It is just that the name might not match the game as quickly as hoped.