At some point during the 2017 season — his first in Houston — Carlos Beltran informed teammates they were lagging compared to others in using the new video replay mechanism to decipher signs between catcher and pitcher. In a piece earlier this month, The Athletic reported Beltran told his new club you are “behind the times.”

Beltran’s admonishment was a key trigger in the Astros devising a system that alerted hitters in real time what pitch was coming, at least in 2017.

In that championship season, the Astros mainly used a camera installed in center field, fed to a monitor near the dugout, and once the signs were decoded, a garbage can would be struck to alert a hitter what type of pitch was coming. The Astros did this hundreds of times and it ultimately led to a series of MLB punishments, including one-year suspensions for now fired GM Jeff Luhnow and manager A.J. Hinch.

It also unleashed speculation that if Beltran knew the Astros were behind, then was a previous employer way ahead? He had spent most of the 2014-16 seasons with the Yankees.

Mark Teixeira, a prominent Yankee from 2009-16, insisted in a phone call with The Post, “I don’t believe any of my Yankee teammates ever broke the rules by passing along signs to hitters in real time. We would have seen it.”

Teixeira, in the fullest public explanation yet, described what the Yankees were doing, and what he assumes Beltran meant by “behind the times.’’ He said his Yankees used modern technology for “old-school” benefits.

For years, players had used TV broadcasts of games to try to determine sequencing and indicators to use if they got a runner to second; that runner could then relay the information to a hitter.

In 2014, MLB expanded replay rules to give managers challenges. Each team was outfitted with multiple monitors and angles from all the television cameras in use for the game. Each team designated an employee to review plays and notify managers whether to challenge.

But the unintended consequence was it gave greater detail of everything happening on the field, including a camera trained on the catcher and, thus, his signs.

Teixeira said a few Yankees — namely Beltran, Alex Rodriguez and Chris Young — and a few coaches used the new equipment as the next logical step up from a TV broadcast, which had a single image and, thus, was not always trained on the catcher’s signs.

If a Yankee thought he deciphered the sequence or indicator, Teixeira said, that player would share it with teammates. If someone reached second base, he was told to see if the opposition kept the same signs. If so, the baserunner could alert the hitter with his own sign.

Teixeira claimed the system was not widely successful. In fact, he said he ignored it because “I thought personally it was BS because by the time they decoded and would get it to me [from second base], my at-bat was over or the pitcher and catcher changed the signs. They were wrong more than they were right. … Anecdotally, I would argue with teammates, ‘You are not good at this. You are trying to give signs, then you get mad at me because I am not good at it either. We are not that good at it.’

“How you get good at it is decode in real time and bang on trash cans. That is way over the line.”

So if what Teixeira describes is all the Yankees were doing, were they violating any MLB regulations?

In a statement given to The Post, MLB said, “After the 2017 season, we learned that a number of Clubs believed utilizing video monitors in the clubhouse and video room to decipher signs so they could later be relayed to a runner on second base was not a violation of MLB rules as long as the information was not communicated electronically to the dugout. As a result, we clarified the rules going forward to expressly prohibit such conduct.”

Teixeira insisted the decoded information was not communicated electronically from 2014-16, but rather by word of mouth.

MLB viewed what the Yankees and other clubs were doing as technically against at least the spirit of the rule, but the league admits the rule wasn’t written clearly enough to differentiate that the replay monitors should not be used like a TV monitor in the clubhouse — and players had been trying to decipher for years off of regular TV, which was not illegal.

The league likened those teams with the new replay monitors as essentially going 65 mph in a 60 mph zone as compared to the 100-plus mph of the 2017 Astros.

MLB considered what the Astros did as way more egregious for multiple reasons. One, it happened in real time to alert hitters what was coming, even with no runners on base. Secondly, it included the creation of an algorithm to decipher the signs that could be relayed to runners at second to alert hitters. Additionally, electronic communication was used in multiple ways and it continued beyond the Sept. 15, 2017, commissioner’s edict that MLB sees as a line in the sand about sign stealing.

On Sept. 15, 2017, the commissioners office penalized the Red Sox for improper use of an Apple Watch and the Yankees for improperly using a dugout phone to call the replay room to learn if a pitch was a ball of a strike — a violation because of contact with the replay official. MLB also stiffened the rules about relaying signs using electronics at that time, and did so again in a memo during spring training 2018 that made it explicit that any clubhouse or video room equipment could not be used to decode signs.

Before that, MLB had a rule that “under no circumstances may electronic equipment or devices be used for the purpose of stealing signs or conveying other information designed to give a club a competitive advantage.”

MLB came to learn that many teams interpreted that to mean no cell phones or computers to transmit sign information to the dugout and MLB determined those teams did not view themselves as cheating or knowingly violating a rule.

In fact, MLB felt the rule had enough loopholes that the commissioner did not come down hard on the Red Sox for the Apple Watch incident (they were fined just $200,000), though that was real-time electronics as texts were sent from the replay monitors to the dugouts via the watch.

Teixeira declared what the Yankees were doing from 2014-16 ventured nowhere near the Apple Watch scheme, or what the Astros expanded to in 2017 with Beltran aboard.

“I sensed certain guys like Chris Young, Alex and Carlos were guys trying to gain an edge,” Teixeira said. “I was a guy playing every day, so I was in the dugout and not hanging in the video room. I heard Chris Young, Alex and Carlos talk about signs more than others.

“But never were they, ‘Teix, we have signs that we can relay to you while you are on deck or at the plate.’ I was old school. They were getting the signs, and if you reached second base they would say, ‘Check if these are them, then you can relay it to the hitters.’ … We are talking the old school way of relaying signs. ‘We think this is the pattern and if you pick up the same pattern at second base, then relay it to the hitter.’ ”

Teixeira insisted, “This is what every team has done over the past few years with video rooms being close to the dugout and [it is] not against the rules.”

Teixeira said he assumes any reference that the pre-2017 Astros were alerted they were “behind the times’’ was based on other teams such as the Yankees using the new video system to decode signs to provide information for potential runners who reached second base.

Yankees GM Brian Cashman told The Post: “Knowing there is no infractions regarding these issues and it being vetted by MLB several times over, I don’t think it’s worth commenting on.” The Post attempted to get comments from Beltran, Rodriguez and Young, but none responded to the requests.

“By the time we had monitors in a video room there was a little bit of [watching during the game] going on,” Teixeira said. “Honestly, I didn’t see anyone take it to the level of real time, run to the field and say, “Mark, it is X sign.’ Most catchers and pitchers were smart enough that if they had any inclination on signs, they would switch them.

“The Astros took that to a whole different level. They used an algorithm in real time to decode and bang on trash cans. None of us even thought of stuff like that. That is next level.

“We would have a couple of coaches and players looking before the game [at video] and if, say, Josh Beckett were on the mound, they would say it looks like consistently it is the second sign once you are on base or the third sign or whatever.

“If there were any shenanigans beyond that, I had zero knowledge. Either I was left in the dark or it did not happen.”

So was it possible Teixeira was in the dark and something more nefarious was ongoing without him knowing?

“If anything were happening on the Yankees, it was not to my knowledge,” Teixeira said. “If it were going on, it was being hidden from me. For the record, I don’t think any of my Yankee teammates were doing a thing. I was plugged in with the coaching staff and the players. It would be akin to a guy on the Astros who played there a long time, like George Springer, not having an idea. That would be hard to believe. How would there be outward cheating and the managers and the players knew, but one veteran had zero idea? I would have had to be very naive and totally in the dark if the cheating were happening and I was completely unaware.”