As free agency kicked off the start of a new football season, the NFL sent a clear message to anyone paying attention:

Colin Kaepernick, you’re still not wanted.

Probably not ever.

Oh, and while we’re at it, it’s pretty clear the owners have every intention of clamping down on any other players who tries to carry on Kaepernick’s legacy.

Rattled by another big dip in the television ratings and an increasing number of empty seats, the league seems determined to banish peaceful protest from the playing field.

While it’s quite a stretch to say those trends are intimately related — injuries, bad games and poor showings by several of the league’s most popular teams were surely bigger factors in the waning popularity — the guys sitting on what remains an enormous cash cow aren’t taking any chances.

Since Kaepernick is the one who got this whole thing started by having the audacity to silently kneel during the national anthem to protest racial injustice — the nerve of that guy! — his career could very well be over.

Never mind that he’s undoubtedly more talented than many of the quarterbacks who still have paying jobs.

Just look at those who have already agreed to new deals heading into the 2018 season.

— Kirk Cousins , who has a losing career record as a starter and has yet to win a playoff game.

— Case Keenum , coming off a marvelous season with the Minnesota Vikings but definitely a candidate for one-year wonder. Related Articles Broncos Analysis: Minus key players, focus is on Vic Fangio to lead staff, roster through adversity

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— AJ McCarron , who has just three starts in four years.

— Mike Glennon , saddled with an awful career record of 6-16.

— Tom Savage , who went 1-6 as the Texans’ starter last season.

— Chase Daniel, the epitome of a journeyman.

— Josh McCown , who is 38 years old and, despite the lack of any apparent success over his long career, keeps landing on his feet.

While all those guys keep cashing checks, Kaepernick was working out privately on a field in Houston , quietly going through the grind with only the help of his personal trainers, apparently still hopeful of restarting his career.

His optimism is likely misplaced.

While there’s always a chance of some owner breaking ranks to sign Kaepernick, the possibility grows less likely with each passing day. If anything, the owners are intent on nipping social consciousness in the bud.

Stephen Ross of the Miami Dolphins probably spoke out loud what most owners are saying behind closed doors when he was quoted as saying his players would be required to stand for the national anthem this season.

Ross quickly backtracked, saying his comments were “misconstrued,” but a statement explaining his position left no doubt that he’s had enough of taking a knee.

“I’m passionate about the cause of social justice, and I feel that kneeling is an ineffective tactic that alienates more people than it enlists,” he said.

There was also a report from the Houston Chronicle that Texans owner Robert McNair doesn’t want to acquire players who have engaged in protests or might be likely to going forward. While the team quickly denied the report, McNair’s stance on such issues is apparent to everyone. At an owners meeting last year, he grumbled that “we can’t have the inmates running the prison” — a remark that prompted most of his players to join arms and kneel before their next game .

Meanwhile, the Seattle Seahawks cut ties with two of their most outspoken players, Michael Bennett and Richard Sherman . While a point could be made that these moves were strictly designed to clear room under the salary cap and rebuild an aging defense, one couldn’t help but wonder if their support of Kaepernick’s protest contributed to the moves.

After clearly being blackballed last season, Kaepernick filed a grievance alleging the owners colluded to keep him out of the league . But it would probably take a mass walkout by all the fellow players to get him back on the field, and that’s not happening.

There’s too much money at stake to risk it all for a single player, no matter how unjustly he’s been treated. Even if all the players could come together as one, chances are their protest would collapse as soon as they miss a few paychecks, just as it did during the infamous 1987 strike when a plethora of big-name players crossed the picket line.

So, as we get started on a new NFL season, Kaepernick can expect to keep working out in solitude, at least until he decides on another line of work.

A bunch of less-qualified quarterbacks will continue to hold jobs.

The only message we can send: