What’s next for the Texans without J.J. Watt and Whitney Mercilus?

It almost feels cruel.

Just when the Houston Texans get the quarterback they’ve been waiting years for, the defense that’s carried the team takes a big hit. On Sunday, two of the Texans’ key defenders, J.J. Watt and Whitney Mercilus, suffered season-ending injuries in the team’s 42-34 loss to the Chiefs. On Wednesday, they were placed on IR, and the team signed Kendall Langford and Lamarr Houston.

The team’s identity for the past several years has been the strength of its defense. The Texans have been able to win an admittedly weak AFC South and land in the playoffs with a 9-7 record the past two seasons with quarterback play that was often laughably poor. The defense was so good that it didn’t matter.

That’s not the case this year. Deshaun Watson at quarterback has transformed the offense and made it one of the most fun to watch in the league. But last season’s top defense is middle-of-the-pack in 2017, ranked No. 15 in total defense.

It’s a tight race in the AFC South right now. The Texans are sitting a full game behind the Jaguars and have the same record as the Titans and Colts. The Texans were already without linebacker Brian Cushing, who is serving a 10-game suspension for violating the league’s policy on performance-enhancing drugs. Losing Watt and Mercilus doesn’t help.

“Yeah, two good players, obviously. Great players. And obviously, we feel terrible for them individually, personally,” head coach Bill O’Brien said Sunday after the loss to Kansas City. “It’s tough to put in all the work that they put in, pouring their hearts and soul into the thing and then have their seasons cut short because of an injury. It’s tough.”

It’s rotten luck for both players, and it leaves the Texans in a bind.

Watt is the best defensive player in the NFL when he’s healthy. He’s a force, with three Defensive Player of the Year awards to his name over his first five seasons.

But the past couple of years have been a tough stretch for Watt. He missed all but three games last year with a back injury that had to be surgically repaired. Now he lands on IR once again with a tibial plateau fracture, which is a break along the top of the shin bone. He had surgery on Monday and will miss the rest of the season.

Mercilus also needs surgery to repair a torn pectoral muscle. Last year, he stepped up in Watt’s absence, which helped Houston’s defense stay on top. Mercilus led the team in sacks with 7.5. In 2015, he was second on the team behind Watt’s 17.5 sacks with 12.

Both were off to a slow start this season. Watt had yet to post a single sack, and Mercilus had just one. But having them on the field occupies offensive linemen and helps open things up for guys like Jadeveon Clowney and inside linebacker Benardrick McKinney.

With Watt out, the Texans are likely to shift Clowney around the formation and have him spend some time at defensive end, according to the Houston Chronicle’s Aaron Wilson. That will help fill the void left by Watt’s absence.

The Texans are also flying former Bears and Raiders outside linebacker Lamarr Houston in for a workout, according to NFL Network’s Ian Rapoport. Houston is also visiting with the Bucs, so there’s competition for his services. But Houston played in just two games for the Bears last year, contributing four tackles and no sacks.

It’ll be a group effort.

It’s hard enough to replace either Watt or Mercilus. Replacing both adequately is impossible.

Rely on the next man up. That’s the obvious answer.

“We have to do a good job coaching and scheming, but that’s the National Football League — guys get hurt and the next guy in the team meeting room at that position needs to step up,” O’Brien said.

Houston will depend on Clowney more than ever. Christian Covington, who came in for Watt on Sunday against the Chiefs, will also have a role. Covington finished the game with three tackles. Last year he posted one sack, in the team’s Week 17 matchup with the Titans.

Ufomba Kamalu and Brennan Scarlett should also get more snaps opposite Clowney. Kamalu played in four games and started one last season, recording five tackles and one sack on the year. He posted one tackle, against the Chiefs. Scarlett stepped in for Mercilus on Sunday and had six tackles.

The reality is whoever takes over for Watt and Mercilus will be a downgrade. But O’Brien says it’s not just on those players.

“I think that’s tough. I think that, but at the end of the day, that’s not an excuse,” O’Brien said. “We have to do better in all three phases.”

There’s more to it than just counting on the next man up. Houston’s secondary is its weakest point. The Texans let A.J. Bouye and safety Quintin Demps walk in free agency. Their top cornerback, Kevin Johnson, should be back on the field soon, but he’s been sidelined since Week 2 with a knee sprain.

Houston gave up 378 yards and five touchdowns to Tom Brady in Week 3. On Sunday, Chiefs quarterback Alex Smith threw for 324 yards and three touchdowns. With the Texans’ top two pass rushers out, the secondary’s job just got a lot harder.

The good news for the Texans is under center, for once. Watson’s late-game heroics kept the Texans in it against the Chiefs in the fourth quarter. Will Fuller is back on the field after breaking his collarbone during training camp, and in the two games since he’s returned, Fuller has already scored four touchdowns. Having Fuller back helped get DeAndre Hopkins going, too — Hopkins also has four touchdowns in those two games.

It’s going to be a difficult road for the Texans with their two best defenders out for the rest of the year, but perhaps this season things will shift and Watson and Houston’s offense will carry the defense for a change.