FOXBORO — It can be dangerous to look at one play in a football game and see it as determinative of larger problems, but sometimes there are such plays. The strip sack of Tom Brady on Monday night in Kansas City was such a play.

What it showed was not all the reasons for the Patriots’ struggles this season, but it illustrated a glaring one of their own making. As the saying goes, it’s not the size of the dog in the fight that counts, it’s the size of the fight in the dog.

On this play, and on too many others so far this season, the biggest dogs have been pacifists.

As most of you know, left tackle Nate Solder has struggled much of the year, especially against speed rushers like Tamba Hali. On the play in question, it would be stretching it to say he struggled — because that would imply he at least put a hand on Hali, which he did not. Yet the greatest tackles who ever played were beaten from time to time so that, in and of itself, is not the issue.

The issue came after Hali went by Solder on his outside shoulder as if Solder had been blindfolded before the play. Hali closed in on Tom Brady from behind like an unseen freight train and blasted him, slapping the football out of his hands. It bounced wildly to the right with Hali in hot pursuit. Solder slipped to one knee initially after missing Hali but got up and began to pursue him.

As Hali recovered the ball, tiny Julian Edelman sprinted back and dove into him to try and dislodge the ball. As he did, three other Chiefs dove on Edelman, one pulling him by his legs off Hali. As this tag-team match went on, a telling thing happened.

Nothing.

Nate Solder did nothing. Sebastian Vollmer did nothing. Bryan Stork did nothing.

They simply stood and watched a teammate barely 200 pounds in the middle of what became five Chiefs, fighting them all for the ball. Their lack of interest in participating was damning. It’s the kind of play that says more about them than they would like.

Solder did chase Hali, but once Hali dove on the ball he stopped and watched, a silent spectator as Edelman fought. At least he didn’t applaud.

Vollmer stood around as well, looking down as if to say, “Oh, my!” And the rookie Stork seems to have already learned from those pacifists in his midst a bad habit, because while Edelman was being pulled and pounded, he put his hands on his hips and watched.

Not a one of them tried to pry a Chief off their little Indian. Not a one of them dove into the pile. What Logan Mankins would have done is unmentionable in a family newspaper, but if he was there he would not have been standing. He would have been with Edelman, probably doing something unthinkable to poor Hali at the bottom of what became a pig pile.

Had any of them done so would Hali have lost the ball? Not likely. Would the Chiefs have lost the game? Not likely. So what’s the issue?

The issue is that pro football is a three-hour street fight. It is not art; it is not science. Some critics aren’t even sure if it’s sport any more. But the medical records certainly substantiate one thing: It’s a dog fight.

And if your biggest dogs want to stand around like friendly labs while the one Chihuahua in their midst is doing all the fighting, it’s going to be not only a long night but a long season.

Some games you don’t play well. Some games you don’t have it. Some games the other guys are better, or at least having a better day. But there is no day when you can’t fight back.

Football players who stand around when the ball is loose or when one of their teammates is pinned to the ground and dragged out of a pile on his back are neither teammates nor football players. They are observers in a game that demands violent action, if you want to win.

Surely those guys wanted to win in Kansas City. They wanted to beat Oakland decisively, but didn’t. They didn’t want to be manhandled by the Dolphins. Yet those things happened, so now the Patriots’ bandwagon has room for people to stretch out. If they don’t play better Sunday night against the undefeated Bengals, there will be enough room to bring a Barcalounger on board.

That’s why Sunday’s game is fraught with meaning. The Patriots of Tom Brady have had bumps in the road before. It happened in 2006 when they lost two straight, then slaughtered the Packers in Green Bay. It happened in 2003 when they were mortified, 31-0, in Buffalo but quickly made that loss meaningless. It happened in 2011 when they lost to Pittsburgh and the Giants, then won eight straight and went to the Super Bowl.

Those guys reacted to doubt with resolve. Then again, those guys aren’t these guys. Those guys wouldn’t stand around as a teammate got pummeled. What will these guys do?

As Tom Brady said repeatedly Wednesday when asked about this team’s future, “We’ll see.”

Yes we will. Sunday night when an undefeated opponent coming off a bye week with a physical defense allowing 11 points a game arrives spoiling for a fight, we’ll see.

The choice then will be the Patriots to make.