The standard job description: Weigh at least 300 pounds, be strong and aggressive enough to push around a man just as heavy against his will, expect to toil in anonymity unless a mistake is made.
A thick skin also is a must—no player holds an offensive lineman to a higher standard than the man who lines up beside him because the unit is literally only as strong as its weakest link.
"With offensive linemen, there's a hierarchy," said Brad Hopkins, whose 188 games at left tackle with the Tennessee Titans was more than any other left tackle in the NFL between 1993 and 2005. "There's a hierarchy of experience, there's a hierarchy of toughness, there's a hierarchy of expectations, and every offensive lineman in that unit has to fall in line.
"They'll jeer, they'll tease, they'll poke, they'll prod and depending on how much you take, that's where you are in that rung of offensive linemen."
A report on the Miami Dolphins' racially charged bullying scandal detailed how the locker-room culture apparently went too far, with several offensive linemen at the center of the harassment case, including Richie Incognito, Jonathan Martin and their offensive line coach.
Their alleged behavior of vicious taunts and racist insults was even unacceptable by NFL locker rooms standards.
Still, NFL linemen believe each man in the unit has to be accountable because they hit, and get hit, more than any other player.
"The other guys in that unit are saying, 'Hey look, we need you to step up.
"I can't be questioning your heart."
And there can be no question about a player's toughness.
Offensive linemen pave the way for running backs and protect star quarterbacks—and take pride in dominating opponents. But they can be an aloof group, sticking mostly to themselves because they feel no one else on the team can identify with their jobs.
In Carolina, the O-line has always been a clique unto itself.
Panthers Pro Bowl tackle Jordan Gross once rented a full-size Winnebago for training camp in Spartanburg, S.C., where players could relax and play cards during breaks from practice and meetings—a little air-conditioned paradise away from the intense summer heat.
The lone rule: Only offensive linemen allowed.
The Denver Broncos offensive linemen prefer not to talk to the media, in a tradition that goes back to the late 1990s. Weekly dinners also are a tradition at most teams with each lineman taking his turn picking up the check all in the name of building the bonds crucial to winning in the trenches.
In Miami, that led to questioning players' sexuality, family heritage and ethnicity, according to a report ordered by the NFL.
Kevin Mawae, who played 16 seasons with Seattle, the New York Jets and the Titans, said a strong leader can nip jokes early to stop someone from crossing the line. The former president of the NFL Players Association also said the union's role is ensuring a fair and safe work environment across the league and that a situation never should get to the point where the union gets involved.
"The team and the coach should have a pulse of what's going on in the locker room," Mawae said. "The greatest coaches do, and they control the message in their locker room. They control the environment. The teams that struggle don't, or the coaches turn a blind eye or are ignorant to what's going on, and that's unfortunate."
But it's not uncommon for players to settle their own disagreements.
Frank Garcia, who played nine seasons in the NFL, said he witnessed a fistfight in 1998 between Panthers offensive linemen Blake Brockermeyer and Norberto Davidds-Garrido just minutes before the start of a game.
Garcia said Davidds-Garrido had taken offense to a joke by Brockermeyer, and all of sudden two 300-pounders were trading punches and wrestling on the floor.
"It was like King Kong and Godzilla going at it," Garcia recalls.
A large chalkboard used by the offensive line for game planning was snapped in half before teammates separated them.
Garcia said things were fine between the two men after the altercation.
Davidds-Garrido, unlike Martin in Miami, decided to fight back—just as he did in training camp in 1997 when he punched Kerry Collins in the eye after Carolina's then-starting quarterback allegedly used a racial slur.
"A lot of times guys make jokes about another guy's wife, girlfriend or even sexual orientation," Garcia said. "And most of the time it's just in good fun. But you have to understand when you push a guy too far, or you've crossed the line, and it's time to pull back."