FOXBOROUGH, Mass. — The Bears came to New England as an underachieving 3-4 football team. When they left, they were a national embarrassment.

It wasn’t so much the 51-23 beatdown the Patriots handed the Bears Sunday, although that didn’t help anything. No, it was more so the antics after the whistle and around the locker room that had everyone shaking their heads again.

How do you make an ugly 51-23 defeat in a must-have game even uglier? You do what Lamarr Houston and Brandon Marshall did Sunday.

Down 48-23 with 3:24 left in the game, Houston finally broke through with his first sack of the season, dropping little used rookie Jimmy Garoppolo for an 11-yard loss. Down 25, most players would probably just get up and dust themselves off — maybe even help the quarterback up.

Houston did the opposite.

The defensive end went in full celebration mode and suffered a knee injury. He’ll have an MRI Monday to determine the severity.

“I probably shouldn’t have celebrated with them blowing us out, but it happens,” Houston said after the game.

Amazingly, it does happen. Lions linebacker Stephen Tulloch tore his ACL earlier this season during a similar sack celebration, which is even more reason why Houston shouldn’t have celebrated like he did. But add in 25-point deficit on the scoreboard?

“He’s got a knee (injury),” Bears head coach Marc Trestman confirmed. “I’m very disappointed for him.”

Not “in” him. “For” him.

Then, moments after the game ended, Brandon Marshall arrived near the entrance to the locker room where reporters were waiting to get in.

“Come on, put y’all’s ears closer to the door,” he said, taunting the media after they overheard him yelling in the locker room following last week’s loss to the Dolphins.

Asked for a comment a few minutes later, Marshall sat at his locker with his jersey off, but game pants still on, and said he doesn’t talk until he gets dressed. That created an awkward scene as a large group of reporters, columnists and cameramen stood by his locker as the wide receiver sat there not getting dressed.

After about 10 minutes, Marshall put a shirt on and stood up for the cameras.

First question: “If last week was ‘unacceptable’ what was this week?”

“That’s last week, brother.”

But what’s this week?

“We lost. Hope I answered your question, but that’s last week.”

To his credit, Marshall went on to answer almost every other question with more effort, including a tough one about why he took himself out of the game on a 4th-and-10 in the second half.

“I don’t win answering that one,” he said.

Fair question. Fair answer. But not to Marshall.

“If a player says he’s fatigued, then he’s not in shape,” Marshall continued. “I love football and I want to play, so you can take that. I don’t give up. I’m a fighter. I’ve always been a fighter. I’ve fought my whole life. So, whatever you’re trying to refer to, it’s whack to me. It’s whack, bro. It’s whack.”

It wasn’t whack. It was a perfectly fair question, especially because Marshall appeared to slow up on his route on third down.

Marshall went on to say that he “probably came out six times this game” and referred to the 4th-and-10 as “bad timing.”

Trestman didn’t have any answers either.

“I don’t know why (Marshall came out). He wanted to finish the game,” the head coach said. “The guys want to finish the game and be out there, so I can’t answer that question.”

Answers seem hard to come by these days. How can a team with so much talent on offense be this disappointing?  Everyone wants to argue about where the blame falls, but honestly, there are very few areas devoid of blame, and it starts up top.

You can blame general manager Phil Emery for the lack of depth on defense and the underwhelming production from his expensive defensive line.

You can blame Marc Trestman for a locker room without an identity. He didn’t want a leadership team. He wanted “a team of leaders.” He has neither.

You can blame Jay Cutler for, well, being Jay Cutler. He’s the same player he’s always been and always will be.

You can blame Brandon Marshall for leading the league in drama and ranking 30th in receptions. The guy supplies t-shirts that say “No Noise,” yet he creates more noise than almost anyone in the NFL. He blames the media by saying they “control the masses,” yet his weekly Showtime show makes him a member of the media too.

You can blame Mel Tucker for a defense with fundamentals that are deteriorating each and every week. It’s not his fault the talent pool is thin, but his own players refer to the scheme as “vanilla” and, more importantly, it’s not working. Rob Gronkowski left Sunday’s game with “dehydration” on a cool, windy New England day. Apparently that happens when you catch nine passes for 149 yards and three touchdowns.

You can blame Joe DeCamillis for a special teams unit that hasn’t been anything but below average for a season and a half, and that’s probably being kind.

The list goes on and on. Really, the only one you can’t blame is running back Matt Forte, who quietly comes to Halas Hall every day and leads by example. He makes his noise on the field by consistently performing on Sundays, which is what really matters. Against the Patriots, he caught six passes for 54 yards and a touchdown, while also rushing for 114 yards on 19 carries.

“I told our team that we aren’t paid to just play the games. We are paid to win the games,” Trestman said.

That must be why the head coach, who is 11-13 in a season and a half with the Bears, is starting to feel the heat.

Sunday, the Bears trailed 38-7 at halftime and those 38 points were a team record for first half points allowed by the franchise. So what did Trestman tell his team at halftime?

“I told them that we were going to define ourselves in how we played the second half, because the first half was inexcusable.”

The same can be said about the season as a whole.