It sounds like Duane Brown will be the Seahawks’ only preseason contract extension this year, with Frank Clark and K.J. Wright having to wait until after the season to see where their futures lie.

A day after we talked about Duane Brown’s possible extension with the Seahawks, they finished it off, adding $36.5 million and three years to this year’s $9.75 million.

As Earl Thomas holds out, some wonder: Why will the Seahawks extend a 33-year-old Pro Bowl left tackle but not a 29-year-old Pro Bowl safety?

We’ve made it clear we’re in favor of paying Thomas, but the Hawks obviously think he is not worth top dollar because speed-based players can fall off the cliff quickly and Thomas has had injury issues in recent seasons.

Good linemen, meanwhile, can play into their mid-30s at a high level, and the Hawks clearly are banking on that with Brown. They figured he’s a good bet at $11 million APY over the next four years, while $14 million APY is too much for Thomas (even if they forgo the injury guarantees and can move on in a couple of years with little cap trouble).

So, if not Thomas, who’s next? Probably no one for now.

Clark is going to want more than Seattle likes to pay defensive linemen. His market could be around $14 million APY, and Seattle was paying top ends Michael Bennett and Cliff Avril less than $10 million. It’s possible John Schneider will look at his massive cap space for 2019 and beyond and feel OK paying Clark, especially with Seattle’s dearth of pass rushers. But it’s more likely Schneider will wait until after the season to see whether he is worth it.

Clark said he has talked to the team about a new contract, but he also made it sound like they are going to wait.

“The thing that we have talked about is just the expectations of me as far as my play for the season,” Clark said. “So, at the end of the day, I know if I do my job on the field, whether it’s here or anywhere else, it’s going to happen. I’ve just got to do my job, and that’s my main focus.’’

Clark seems prepared to leave, if he doesn’t get the right deal in Seattle.

“I don’t know what’s going to happen,’’ he said. “You never know what’s going to happen in this game. I watched a lot of stuff happen this past season — you know what I’m saying? I didn’t know I was going to be coming here and six of top players would be gone.’’

One of the top players still there who certainly deserves a new deal is Wright. Logic says to pay him: His game is built on length and savvy, and he is a great leader. The 29-year-old should be good for another four seasons, so Seattle should be fine paying him $8 million a year (his last deal was $27 million over four years, and he’s making $7.2 million this year).

But the Seahawks apparently have not talked to Wright yet — and he is fine with that.

Getting a third deal to stay in Seattle “would be cool. That would be good,” he said. “But it’s not up to me. I’m going to control what I can control. I’m not going worry or stress or lose sleep over anything that’s not in my power.”