There are transformative events for every franchise, moments that come to define a particular season or era and often shape the course of that team’s immediate and long-term future.

What happened in Sunday’s meltdown against the Rams likely will be one of those events, and as a result, the Giants may never be the same.

51-17.

This was just the latest moment of ignominy for a team that had been expected to contend for a playoff spot and perhaps even a Super Bowl title. And with eight games to go, there will be more opportunities for further humiliation. But unless there is an unexpected and dramatic turnaround for this team, the watershed moment will have occurred on a dank, overcast, misty afternoon at MetLife Stadium.

It has become increasingly obvious that Ben McAdoo has lost his team, and the woeful effort put forth in one of the most humiliating losses in franchise history has all but ensured his ouster. Perhaps it means general manager Jerry Reese also will be swept up in what team owner John Mara surely will see as an opportunity to chart a new course.

51-17.

“Historical loss in many ways,” McAdoo said Monday afternoon. “There’s no excuse for it. It falls on my shoulders. We played bad team football in all three phases.”

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He insists his team didn’t quit on him, or on each other.

“I watched the film,” he said. “I saw no sign of quit.”

Small consolation, even if McAdoo is ignoring what appeared obvious about a team that looked disinterested.

It was the Giants’ worst home loss since 1964, when Mara was 9 and would cry after watching Giants teams presided over by his father lose in similarly gory fashion. Mara now is 62 and still has that little boy’s emotion in him, if not the tears. He seethed from the owners’ box on Sunday and was so furious about the embarrassment and the empty seats that he stormed out early and went downstairs to the locker room.

He has spoken only once during the season, and that was a few days after the team’s only victory in a Sunday night game against the Broncos. He expressed support at the time for McAdoo and Reese, but that support was not open-ended. He was satisfied with the win but knew much more had to be done for him to be convinced to retain one or the other — or both. “It showed me we’re 1-5 instead of 0-6,” he said of the win over Denver. “It’s a step in the right direction, but it’s just one step.”

Now, it appears, this may turn out to be a housecleaning the likes of which the Giants haven’t seen since 1978, the year “The Fumble” was the transformative event that set sweeping changes in motion that dramatically altered the direction of the franchise.

The Giants’ coach back then was John McVay, whose team couldn’t hold a last-minute lead against the Eagles and instead botched a handoff that led to one of the most demoralizing defeats in team history.

McVay and general manager Andy Robustelli were fired at season’s end, and the Giants’ savior turned out to be a burly, bespectacled GM named George Young. The Dolphins’ personnel director was the compromise choice agreed to by the feuding Mara family (Wellington and his nephew, co-owner Tim Mara, were not speaking to one another). Young first hired Ray Perkins and then Bill Parcells, and the Giants were transformed into two-time Super Bowl champions.

This time, oddly enough, it was McVay’s grandson, Sean, the wunderkind first-year coach of the Rams, who may have hastened the eventual change of direction. Sean McVay, who doubles as the Rams’ offensive coordinator, has done a phenomenal job of turning around the Rams and turning Jared Goff into the kind of big-time quarterback they envisioned when they took him at No. 1 overall in the 2016 draft. The duo picked apart Mara’s team with a surgeon’s scalpel, outcoaching McAdoo at every turn.

Where John McVay left the Giants with “The Fumble” and its aftermath, Sean left Mara’s team to clean up after a 52-yard touchdown pass on third-and-33 in the second quarter. It wasn’t the kind of mind-numbing, game-deciding play that “The Fumble” turned out to be, but it certainly was an appropriate metaphor for all that has gone wrong with this year’s team.

51-17.

The score that ultimately may lead to the kind of change not seen around Mara’s team in nearly half a century.