Are we sure Sam Darnold is the only member of the Jets offense with mono?

The Jets offense looked sluggish, sleepy and sick with its starting quarterback watching from home on Monday night. The unit could barely function and the Jets fell to 0-2 after a 23-3 loss to the Browns. It was the Jets’ seventh straight loss at home, dating back to last year.

“We’re going to have to look at all of our guys and just see who is doing their job and who’s not,” coach Adam Gase said. “Do we have to move pieces around? Do we have to change some things up?”

The news went from bad to worse for the Jets with backup quarterback Trevor Siemian exiting the game in the second quarter with what looked like a gruesome ankle injury. He was replaced by Luke Falk, who was signed off the practice squad Monday afternoon.

Some struggles on offense were to be expected with Darnold sidelined after being diagnosed with mononucleosis and with the team losing starting receiver Quincy Enunwa this past week. But the Jets were embarrassing for most of this one at MetLife Stadium. They had [minus]-13 net yards passing in the first half as Siemian and Falk struggled to complete passes.

The Jets finished with more punts (seven) than passing first downs (six).

“We’ve got to get better at what we’re doing,” Gase said. “We can play so much better than this. The details of what’s going on in all three phases can get a lot better and it’s going to have to. We’ve got a long way to go.”

The Jets relied on a heavy dose of Le’Veon Bell, who had 68 rushing yards on 21 carries and 10 catches for 61 yards. When Siemian went out they ran seven straight plays on which Bell touched the ball.

Falk played better in the second half, but the Jets offense still failed to reach the end zone. Falk went 20 of 25 passing for 198 yards. Siemian was 3 of 6 for 3 yards.

The offensive line was abysmal. Left tackle Kelvin Beachum had two holding penalties, a hands to the face penalty on a fourth down and allowed three sacks by Browns outside linebacker Myles Garrett.

“We’ve got to take a hard look at this and figure out what’s going on,” Gase said.

Garrett was the one who injured Siemian on a dirty hit. He crushed Siemian near the Jets sideline and was flagged for roughing the passer. The quarterback’s left ankle bent in an unnatural way and he was out for the remainder of the game.

Falk entered the game to cheers of “Luuuuuke” from the Jets crowd. The former Washington State star was the Jets’ fourth quarterback entering training camp and was signed to the practice squad after rosters were reduced. He threw a nice 36-yard pass to Robby Anderson in the third quarter, but the drive stalled at the Cleveland 11 after the Jets went for it on fourth down.

On the following play, Browns quarterback Baker Mayfield hit former Giants star Odell Beckham Jr. on a quick pass that he took 89 yards for a touchdown to make it 23-3.

The Jets defense had played pretty well before giving up that long Beckham touchdown. But you knew Beckham would break out at some point, especially after Jets defensive coordinator Gregg Williams poked the bear Friday by questioning whether Beckham was a dynamic player. Those comments looked stupid at the time and even worse as Beckham cut through his defense for a long score. Beckham had six catches for 161 yards and the score.

After the game, Beckham said, “Who?” when asked about Williams before complimenting the coordinator.

“He said that? Jesus,” Mayfield said. “Next question. Not a dynamic football player?”

The Jets’ locker room was despondent after this loss. High hopes for the season have crashed in the first two weeks. The defense played decently other than the long pass to Beckham, but the anemic offense did nothing.

“It’s not about them. We’re a team,” nose tackle Steve McLendon said. “We’re a team. We’ve still got to stop them no matter how many times the defense is on the field. We have a job to do. We were well prepared for this game. We knew them. They knew us. We just didn’t answer the bell.”

Now, the Jets have a short week to prepare for the Patriots on Sunday. New England has outscored its first two opponents 76-3, so the Jets are going to be heavy underdogs to put it mildly. They also have to figure out whether Falk will be the starting quarterback or if they will try to sign someone or swing a trade. Darnold is not expected back for at least three weeks and Siemian’s injury looked very serious.

“We’ve got New England coming up,” Bell said. “We’ve got to go back to work on Wednesday, watch the film and have a good week of practice, get better on the details and execute. We’ve got the playmakers to do it. We just have to make it happen.”