Never mind that Patrick Mahomes got knocked silly and out of a game barely a week ago. He was always going to play Sunday against Buffalo, and because it’s the AFC Championship — instead of, say, Week 3 of the regular season — the only way the Chiefs’ star wouldn’t have cleared the NFL’s concussion protocol is if he had a visible dent in the side of his head.

That’s the danger of concussions. Despite all the advances in science, you can’t see a concussion in real time, the way an X-ray will confirm a torn biceps or bruised knee. We know the damage repeated hits to the head cause over the long term, but only by studying autopsied brains. So even the best doctors today can only note the symptoms when they occur (confusion, headaches and nausea, among others) and take the player’s word on when they stopped, then guess when it’s safe to resume normal activity — let alone an activity as abnormal as pro football.

That was good enough for Mahomes.

“I actually just got out of the protocol,” he announced after practice Friday. Mahomes grinned and looked like the happiest, healthiest 25-year-old alive.

“The week has just been a bunch of testing, a bunch of different things just to make sure that I’m good to go and there’s no lingering effects or anything like that, but everything’s been good,” he added. “I’ve went through what all the three, four different doctors have said, everything’s looked well, and I’m out of it now.”

Every time a franchise quarterback rushes back onto the field after a very public brain-rattling, their fans, agents, team owners and commissioner Roger Goodell all keep their fingers crossed until they cramp. Troy Aikman and Steve Young did so more than once during long playing careers and both, fortunately, showed no lasting damage and carved out lively second acts in television.

But things were different when they left the game some 20 years ago. Concussions were considered little more than an occasional occupational hazard, laughed off as “a visit from the Sandman.” Ballplayers worried about losing a place in the team long ago learned the trick of grabbing a knee or some other body part to buy time while they struggled to clear their vision or simply stand squarely on two feet.

“There was a chance back in the day that Patrick comes back in the game,” Kansas City coach Andy Reid told reporters the day after Mahomes was laid low in a game against the Browns. “You saw him run up the tunnel. By the time he got to that point, he was feeling pretty good.”

Thankfully, those days are mostly behind us. The NFL, chastened in part by a $1-billion-plus settlement with retired players found to have suffered neurological problems, no longer tries to elide the dangers of concussions. Every team boasts a top-shelf medical staff, and the monitoring begins the moment players get hauled into those pop-up blue medical tents on the sideline. The league’s five-phase protocol to clear players to return to practice and games, first put in place in 2009 is based on the latest medical advice and signed off by a neurologist who works for the NFL but not the team.

Players, too, can no longer claim they don’t know the risks involved. But the rewards, immediate fortune and maybe lasting fame, almost always outweigh any potential danger lurking two decades or so down the road. For someone like Mahomes, already the best young player in the game and another big stage already set, the temptation to put his thumb on the scale is even greater.

“Just say he has a headache on Friday, but previous three or four days he’s fine,” Brett Favre told Pro Football Talk in an interview last week. “Is he gonna tell them? I doubt it. He wants to play. …

“Up until 10 years ago there was no protocol in place, and once you felt better — which could be three or four hours — you were back out playing,” Favre added. “He will want to play.”

That cat-and-mouse game will continue until medicine devises a test to determine whether a player has been concussed on the spot, how severely and when his brain has healed enough to resume playing. Researchers have begun focusing on the presence of certain proteins in the blood post-concussion that may provide answers, but those are still a long way off. In the meantime, it’s up to every player to protect himself.

“When you’re in the moment, and you’re young, you’re bulletproof, man. But I’m 51 years old,” Favre said, “and I’m wondering what tomorrow will bring, because of concussions more than anything.”