Vic Fangio has been around long enough to wear an old wristband that reads “Keep Pounding’’ in support of Sam Mills, the New Orleans Saints’ Hall of Fame linebacker he coached in the 1990s who died in 2005.

He’s been around long enough to wear another old wristband that reads, “All Things Are Possible,’’ supporting O.J. Brigance, a linebacker he coached at Baltimore in 2000 who suffers from Lou Gehrig’s disease.

The point isn’t just that Fangio has been around long enough to keep things in perspective, considering no one needs tragedy to put sports in perspective. It’s that he’s been around long enough to have seen friends go through it all, good and bad, in football and out, certainly in opening performances by his defense in Indianapolis that shut down Buffalo in 1999 and ones like Sunday, when his Dolphins defense was laid open in Los Angeles.

“It was a ‘W,’” he said, offering a grim smile about the Dolphins’ 36-34 opener against the Chargers.

The run defense was awful. It couldn’t get off the field on third down. Thirty-four points sums it all up.

“Good enough to win a shootout but not good enough to win a lot of games,’’ Fangio said.

Here’s the larger point: If this is the big question from the Dolphins opener, if this defense is the concern in the big way fans frame it after just one week, this season is going to be just fine when the dust settles. This defense will be good. It should be very good.

That doesn’t mean they go into New England and shut down the Patriots on Sunday. It means there’s good talent on this defense, and Fangio has been around long enough to show you he knows what to do with that. A third of NFL defenses run his system for a reason. The Dolphins have the original.

He’s been around long enough, too, to know if the target gets put on either his players or himself, that’s no real choice.

“I think most of that as my fault,’’ he said of the opener. “Didn’t have the guys ready to play to play the kind of game they had to somewhere along the way. I didn’t do the job of preparing them for the run game.”

Here’s the bottom-line of the Chargers getting 234 rushing yards and those 34 points:

“We went into the game not letting (Chargers receiver) Mike Williams have a big game,’’ Fangio said. “We did accomplish that, but we gave up too many rushing yards, which led to four third-and-1s and four third-and-2s.”

Fangio’s defense typically stands out in these stats: third-down defense and red-zone defense. They didn’t Sunday. The Chargers converted 9-of-15 third downs and scored touchdowns on 4-of-5 trips to the red zone. These are the exact areas the Dolphins’ defense needs to improve after ranking 24th in each last year.

The question always was how quickly this defense acclimates to a system philosophically opposite of what they’ve been doing for years. There has to be a quick learning curve for both sides. Maybe Fangio marries the past to the present. Maybe the sparse-but-winning blitzes showed. Or maybe they were winning because they were so sparse.

There’s no pattern to Fangio’s first years with teams. Take his last three teams. His San Francisco defense finished second in scoring his first year in 2011.

“We inherited five really good starters and got five other good starters,’’ he said.

His Chicago defense got lit up for three touchdowns by Green Bay’s Aaron Rodgers its first game and finished 31st in scoring in 2015.

“The cupboard was bare when got there,’’ he said. “Even the cockroaches weren’t home.”

Then there was Denver, where the cupboard was full and his first defense finished second in the league.

“Every situation is different,’’ he said.

This defense has talent, even with the loss of cornerback Jalen Ramsey in the summer. The talent didn’t show up in the fist game, when the top linemen lost one-on-one battles much of the day, and the inside linebacker idea was exposed as a possible concern with free-agent buy David Long getting less time than Andrew Van Ginkel.

You don’t have to worry about Fangio’s perspective. He’s 65. He sees a league copying his ways. He also has a third bracelet on his left arm, one from Chicago Bears trainer Will Rogers for a young daughter, Charlotte, who was suffering from cancer.

“She’s fine now,’’ he said.

He’s seen it all. He’s seen defenses start strong and start out like Sunday. If this is the Dolphins’ big worry, there’s not a lot to worry about.