No one writes off Albert Pujols if he’s in a slump. They figure he’ll battle his way out of it. No one questions Peyton Manning if he throws three interceptions in a game. Off day, they say. And no one will get down on Kobe Bryant if he shoots 8-for-24. The shots will fall tomorrow.

But if the most-accomplished boxer loses decisively or even wins ugly sometimes, the perception of him can change radically and in an instant.

Take Juan Manuel Lopez, who fights Steven Luevano on Saturday in New York City. The Puerto Rican junior featherweight was the next great star until he struggled to beat Rogers Mtagwa and now he’s perceived as vulnerable, at least until another dominating performance.

Another example is Kelly Pavlik. The middleweight champion was one of the fastest-rising stars until he stepped up in weight to fight Bernard Hopkins and lost a one-sided decision. The monster who twice beat Jermain Taylor suddenly had glaring flaws.

Such is the lot of elite boxers, who are great one day and all too beatable next. Some dismiss such summary judgments as meaningless drivel but acknowledge that they have long been a part of the sport.

“It’s common and it’s very, very short-sighted,” said Bill Caplan, a Hall of Fame boxing publicist. “I lose patience for sports writers and fans who say a guy was never that good if he doesn’t have a great, A-plus night. Fighters are like any athletes — they have bad nights. And the matchup of styles is so important.

“The point is that someone shouldn’t necessarily be diminished because he didn’t take his opponent out or win easily.”

The power of perception can have the opposite effect.

We refused to believe that Muhammad Ali was no longer “The Greatest” until Larry Holmes proved it in the ring. We couldn’t accept the fact that Mike Tyson was beatable even after he lost to Buster Douglas and Evander Holyfield. “Iron Mike” was actually favored in the rematch with Holyfield, which ended with a Holyfield missing a portion of his ear.

“Jack Dempsey lost 10 out of 10 rounds in the first fight with Gene Tunney but was favored in the rematch,” boxing historian Bert Sugar said. “It was as if the first fight didn’t matter.”

That type of skewed perception is reserved only for the legends of the sport, those who we desperately want to believe have one more great fight left in them. Most fighters don’t fall into that category. And most fighters pay a price if they slip up even once.

One reason for that, several experts agreed, is the infrequency with which the sport’s biggest stars fight. A titleholder or top contender might fight twice a year, which creates an exciting sense of urgency but less room for error.

A baseball pitcher can have a bad start but he can come back less than a week later and redeem himself. That’s how it was in boxing in the old days, when losing — even losing badly — didn’t matter as much because fighters had the chance to make amends very soon afterward.

“Once upon a time Sugar Ray Robinson fought Jake La Motta twice in three weeks ÔǪ and once in between!” television analyst Larry Merchant said. “The fact he lost the first fight was quickly canceled. In terms of their images, fighters have a lot more at stake today. ÔǪ They don’t have the chance to come back in five days.

“The guys who have the right stuff, though, they come back and change minds.”

Shane Mosley would fall into that category. The five-time titleholder was all but written off after he lost a close decision to Miguel Cotto and then struggled before stopping Ricardo Mayorga in the 12th round in September of 2008.

He was getting old. He wasn’t as fast, wasn’t as sharp. So what happened in his next fight four months later? He kicked the you know what out of one of the most-feared fighters in the world at the time, Antonio Margarito.

Once again perception was wrong.

“Mosley was fighting a very strong, unorthodox, awkward fighter in Mayorga,” Merchant said. “So it took him time to knock him out. So what? To knock a guy like that out and then be declared a dead man can only happen in boxing.”

Another reason perception can change so quickly is the preoccupation with perfection, meaning it’s somehow a sin to lose a fight even though virtually every fighter in history has lost.

Pavlik might be the best contemporary victim of that plague. He was undefeated and blazing hot after his victories over Edison Miranda and Taylor and then made the ill-fated decision to fight Hopkins at light heavyweight, a big-money event against an older foe.

We know what happened. Pavlik was outclassed by a bigger and better fighter, after which observers were compelled to reassess the loser. He went from a tough, hard-punching wrecking machine to a one-dimensional fighter who could be handled by a big, good boxer.

Pavlik, who also has had health issues, has beaten Marco Antonio Rubio and Miguel Espino since the Hopkins fight and is still rebuilding his image.

“Pavlik fights above his weight class against Bernard Hopkins, loses decisively and suddenly his rocket seems to be grounded,” Merchant said. “And it could take him who knows how long to restore his reputation, depending on what opponents are out there and what fans are paying attention to. It turned out the guy was sick (against Hopkins) and had other physical problems. He went ahead with the fight when he probably shouldn’t have. And he fought in a weight division he had never fought before against a great old pro. The judgment still stands. If the guy made mistakes in and out of the ring, then fair enough.

“ÔǪ I just think making these cosmic pronouncements about whether a guy is over the hill or shot or the next great thing based on one or two fights is like talk radio and internet blather. It doesn’t mean much.”

Floyd Mayweather Jr. might actually feel trapped by perception. Some of his critics suggest he’s not necessarily afraid to fight anyone — including Manny Pacquiao — but is afraid of losing the zero in his loss column.

They would argue that he believes maintaining that zero assures his rightful place in history. The fact that almost every great fighter has lost multiple times — Rocky Marciano being the greatest exception — doesn’t seem to matter.

“I think he might be afraid of losing because of his legacy,” Sugar said. “He’s told me he’s the greatest fighter ever because Sugar Ray Robinson lost and he never has. That’s how he thinks.”

And, finally, boxers generally are held more accountable for their performances because they have no teammates.

If Pujols goes 0-for-4 and the Cardinals win, no one cares. If Manning struggles but the Colts win a defensive struggle, then OK. And if Bryant can’t find the basket and the Lakers win, then no one will remember the superstar’s bad night.

Boxers, like all athletes in individual sports, succeed or fail alone. There’s no place to hide.

“They’re out there in their underwear, basically naked to the world,” Sugar said. “What they do in the ring is plainly evident. It’s easy to say, ‘Well, he’s a bum or he’s not a bum.'”

Lopez can prove he’s anything but a bum by scoring a spectacular knockout or perhaps simply dominating Luevano on Saturday night. Then, hallelujah!, he’ll immediately regain his status as the next great thing even though he’s the same fighter he was before he met Mtagwa.

The point here is that Lopez’s ability as a fighter doesn’t change with the wind. It’s our opinions that do that.

Michael Rosenthal can be reached at [email protected]