Call Sunday’s game many things.

Call it the day the Patriots’ defense got manhandled, the very defense we’ve come to believe was as tough and resilient as a junkyard dog that hadn’t eaten in a week.

Call it the day Matt Cassel looked like the inexperienced quarterback he is.

Call it the day the Patriots finally turned their lonely eyes to the injured Tom Brady.

Call it the day the Pats’ touted offensive line was pushed around for much of the afternoon.

Call it the day Bill Belichick stood on the sideline looking like just another coach with no answers, a role we haven’t seen in a long time.

Call it the day the Pats got booed in Gillette Stadium.

Call it the day people were all but tripping over themselves to get out of the stadium early in the fourth quarter, and it wasn’t because they were trying to beat the crowd to Patriot Place.

Call Sunday’s game many things.

And call it one more thing — the most important thing.

Call it the day reality hit this team, and all the rest of us, right between the eyes.

Because ever since Brady went out in the first quarter of the first game against the Chiefs, Belichick and this Patriots team managed to keep reality locked inside its cage.

They did that by eking out a home win over Kansas City, even though it came with a little help from the Chiefs. But Cassel was adequate, and they survived.

They did it again against the Jets, one of those perfect game plans, helped along by the fact the Jets were awful, about as imaginative as an accountant.

So we all believed, right?

Believed in Belichick, the best coach on the planet.

Believed in the defense.

Believed in the Patriots, this proud team that long ago proved it knew how to win.

Until Sunday, when it was like the emperor had no clothes.

For those weren’t the ’72 Dolphins the Pats were playing.

They weren’t Chuck Noll’s Steelers.

They weren’t even last year’s Giants.

They were the Dolphins, and they came in here having lost 20 of their last 21 games, and were 0-2 this season.

They were a team with a new coach and a new quarterback and a slew of new faces, a team that wasn’t supposed to come into the snake pit that’s Gillette Stadium and even be in the game, never mind humiliate the Patriots.

This was the Pats we’ve come to know?

No.

But this was reality.

It’s been too easy the last few years, of course. Teams aren’t supposed to win 21 straight regular-season games. Not in the salary-capped NFL. Not in a league where the party line always has been, On any given Sunday . . . Not in the best football league in the world, one full of elite players, the best of the best.

And we’ve all grown used to it — you, me, the Patriots themselves. As if this had become the way of the world.

Take away the MVP of the league?

No problem.

We’ll just plug in a kid who doesn’t have any NFL experience and didn’t have much in college, either, right? And the beat will go on because we are the Patriots, the system is king, and all we have to do is replace one body with another.

That’s been the attitude, and it’s easy to see why it’s evolved the way it has. Why doubt the Pats when they had won three Super Bowls in the last seven years? Why doubt them when they had won 21 straight games and had become the standard-bearer of excellence in the NFL, the franchise everyone else aspires to be? Why doubt the Patriots when every Sunday was just another party, complete with the chips and dip?

Until last Sunday, when the Dolphins came in here and had people rushing to the exits early in the fourth quarter, the suspense as gone as Saturday night, as if we all woke up and it was one of those woeful years in the early 1990s when all the real games in the NFL were taking place somewhere else.

Until last Sunday, when reality hit all of us right between the eyes.

Which doesn’t mean that the season is over, of course.

If the first three weeks of the season have taught us anything, it’s that there is no heavyweight out there — not in the AFC; not yet, anyway. The Colts are 1-2, the Steelers already have lost a game, and there’s no team that’s shown it’s dominant enough to run away and hide.

So the Pats are still very much in the picture until they prove they are not, for this is still a team with a lot of very good players, coached by Belichick. They are still the big dog in the neighborhood, the one no one wants to walk by.

Sunday did nothing to change that, regardless of how much it took everyone by surprise.

And the most surprising thing?

The way the Patriots were pushed around. It’s one thing to lose. It’s another to be slapped around by the Dolphins. It’s another thing to be embarrassed, to see people heading for the exits like they’re trying to get away from a bad accident.

So you would expect the Pats to grab the bye week like a drowning man grabs a life raft and come back as if Sunday was just an aberration.

We’ll see.

For now, Sunday was many things, all of them bad.

The day reality hit all of us — you, me and the Pats themselves — right between the eyes.

Seeing people running for the exits early in the fourth quarter will do that.

breynold@projo.com