Unless he comes in, tail tucked, this week, Kam Chancellor will do irreparable damage to himself, his teammates and the franchise. He’s the most foolish man in sports.

It pains to write this, knowing how well-regarded he is. But at the moment, Kam Chancellor is the most foolish person in sports. And that is saying something, with NFL Commissioner Roger Goodell seeming to dominate the candidate list.

Tattered as is Goodell’s reputation following his embarrassing judicial rebuke in Deflategate, he hasn’t lost any personal wealth and probably will emerge with only dents and scratches.

As his nonsensical holdout passes into 40 days, Chancellor now runs the risk of not only losing millions, he could irreparably damage relationships with coaches and teammates. Until this week, players could express their emotional support for Chancellor as a principled stand for an individual’s true worth, with the slight hope that if he backs down the Seahawks, it potentially means leverage for them against the club in future negotiations.

But it’s game week, not training camp or exhibition season whose exercises an athletic talent like Chancellor can skip without significant harm.

This week counts.

No matter the brave words offered in support of Dion Bailey, the undrafted free agent from USC who is ticketed to start at strong safety Sunday in St. Louis, the Seahawks are much diminished by Chancellor’s absence. He’s the best in the game at what he does, adding menace that opponents often find sufficient to alter play-calling and players.

Bailey may someday emerge as another benchmark story in the Seahawks’ remarkable UDFA chronicles. But this week he’s a nervous rookie making his debut on the road in a dome against a division rival while trying to replace one of the NFL’s most ferocious competitors.

Bailey is, as the Seahawks like to say with a well-rehearsed shrug, the next man up.

I ran into Richard Sherman in the Seahawks locker room Monday, and asked him how the defense looked without Chancellor. He was stoic almost to the point of sounding irritated.

“It looks the way it always looks without him,” he said. “We play next man up. We played without him before. We play without him now. Same old.”

Well, not quite. Injuries are an accepted part of the game. Chancellor’s holdout is entirely voluntary, and that’s what will chap teammates. Back-to-back Super Bowls in this era was incredibly hard. Three in a row is unprecedented.

Particularly with a pointless action impeding the feat.

Regardless of where one’s sympathies lie, the Seahawks have no viable recourse to improve Chancellor’s contract in the second year of four-year deal, a deal that is hardly bad but no longer top-of-market. There is no NFL rule against a re-do, but there is large pressure on the Seahawks from the other 31 club managements to not give in, because buckling would put pressure on all team managements, not just the Seahawks.

Everyone closely connected to the business of the NFL is watching this drama. They know that unless Chancellor shows up this week, there’s no decent way out for him. If the Seahawks lose Sunday, he will be partially blamed. If they win, Bailey will be seen as a viable replacement. Neither is exactly true, but whatever support Chancellor thought he may have had will vanish as feelings harden.

If Chancellor shows up after the first game without an improved deal, all parties will attempt to say everything is good. But it will be a lie. Damage will have been done.

How can GM John Schneider believe that Chancellor won’t create the same headaches in 2016? How can Chancellor provide his usual intensity when he feels so wronged?

If Chancellor continues to hold out, and the Seahawks decide to trade him, each game diminishes his trade value, further hurting the club. Because of the salary cap, there’s little chance a player of value can be had, because the acquiring team will have to work up a renewed contract for Chancellor better than what he has. Some significant player would likely have to be cut.

Which is why the trade compensation would most likely be draft choices, which do nothing for 2015. The Seahawks may be better off waiting until after 2015 to trade him, when his value for a full season of play will be higher.

A return after the first game could probably be made to work in some fashion, but the scrutiny of Chancellor’s play would be ruthless and wrenching. He dares not get hurt.

Coach Pete Carroll has worked up a plan to guide this team through the ashes of the worst loss in Super Bowl history to get back to where they were. The plan didn’t include one of his best players and leaders voluntarily going foolish.

“Next man up” is a good working mantra for any team, but this isn’t an injury or a retirement. The club already had to burn a 2016 fifth-round draft choice to acquire a backup safety, Kelcie McCray, to do the backup job from which Bailey inadvertently graduated.

Chancellor stunned the sports world last season when he leaped over the offensive line in an attempt to block a field goal. He’s about to stun it again with a leap off the NFL cliff.