It might not seem like it if you watch Rex Ryan and the rest of the New York Jets staff on HBO’s "Hard Knocks," but football coaches really do need to be extra careful about what they say these days — especially while the cameras are rolling. Greg McMackin learned this the hard way before last season when he told what he thought was a joke and it wasn’t perceived that way by a lot of people, including his bosses.

The lesson seems to have taken hold for the University of Hawaii head coach — and now, in a different kind of situation. After UH’s season-opening 49-36 loss to USC on Thursday, McMackin was very careful with "the c-word," as our editor Paul Arnett has so aptly termed it. You know, concussion.

Quarterback Bryant Moniz got whacked hard on the noggin by USC linebacker Michael Morgan at the end of a third-quarter scramble. The party-line reason from McMackin and other UH personnel for Moniz’s not returning to the game is a "possible head injury" or an "apparent head injury."

With apologies to Tyler Durden, the first rule of concussions is don’t talk about concussions — except to make sure you’re not ruling out that your player might not have one.

"I wouldn’t say he has a concussion," McMackin said after the game, when asked of Moniz’s condition.

HEAD INJURY or concussion. What’s the difference?

Well, not all head injuries are concussions. And if UH were to say Moniz has a concussion and it turns out he doesn’t, that could bench the starting quarterback for at least a game.

Spurred by more concern about brain injuries and research on the cumulative effect of multiple concussions, the NCAA mandated last spring that member schools develop written policies for dealing with such injuries.

Team doctors and athletic trainers are supposed to have the final say over coaches or the players themselves regarding return to activity. That was always the rule, but now everyone is on notice.

McMackin and offensive coordinator Nick Rolovich both said the first priority is Moniz’s health, and he will be evaluated daily before being allowed to even return to practice. It’s obvious they care about Moniz, the person.

Yesterday, Moniz said he hasn’t experienced headaches or dizziness, which are two symptoms of a concussion.

It was widely reported after last year’s Boise State game that Moniz left that contest because of a concussion. He came back the next week to play at Nevada.

If the official diagnosis is concussion this time, Moniz might not be medically cleared to play at Army or even get on the plane to fly to the East Coast. That’s "maybe" because there would be nine days between the injury and the next game, and sometimes clearance for return to activity is a week.

We are also told now by doctors that there really is no such thing as a "mild concussion."

THE PARADOX of football has never been more apparent. Nobody except a few sickos wants to see players get hurt. But that same risk of injury — and especially an ability to put fear aside after an injury — makes the achievements seem more meaningful. Physical courage is the most respected attribute among players. It’s a big part of why most of us love the game.

The problem is a player can feel fine and not experience symptoms and a brain injury might not be healed yet.

It’s understandable that UH doesn’t want to say there’s a concussion. But it’s the school’s responsibility to fully buy into another c-word with any head injury.

Caution.

Reach Star-Advertiser sports columnist Dave Reardon at dreardon@staradvertiser.com, his "Quick Reads" blog at staradvertiser.com and twitter.com/davereardon.