FLOWERY BRANCH — Tyson Clabo speaks softly when he’s standing at his locker. Put him on the football field and it’s a different story.

Same for Harvey Dahl, who goes out of his way to draw as little attention as possible — until he puts on his helmet and shoulder pads.

These two very large men, both of whom went undrafted out of college, have set the tone for one of the NFL’s best-kept secrets: the Atlanta Falcons’ offensive line.

While most of the kudos for a surprising season have gone to running back Michael Turner, the NFL’s second-leading rusher, and quarterback Matt Ryan, a rookie playing with the poise of a 10-year veteran, the guys in the trenches have gone unnoticed.

On the right side, there’s Clabo at tackle and Dahl at guard. The center is Todd McClure, the dean of the group. Justin Blalock holds down the left guard spot, and Todd Weiner has filled in ably at left tackle while rookie Sam Baker recovered from back surgery.

Baker could be back for Sunday’s crucial game against Tampa Bay, adding a little first-round star luster to a most nondescript group, with not one trip to the Pro Bowl among them.

But Turner wouldn’t have run for 1,269 yards and tied a franchise record with 14 touchdowns if not for the gaps created by those up front. And Ryan wouldn’t be the ninth-rated passer and have one of the league’s lowest sack totals (13) if not for five guys giving him time to throw.

"They’ve been the hardest-working group on this team," Turner said Wednesday. "They wanted to prove something and show they actually could play in this league."

Coming into season, the offensive line looked to be perhaps the shakiest unit on a team filled with holes after Michael Vick was sent to prison for dogfighting and coach Bobby Petrino bolted for Arkansas.

Clabo was cut four times — twice by the same team — before he landed on the Falcons’ practice squad in 2005. He finally got on the field the following year when injuries struck, and made 11 starts last season on a team that went 4-12.

Then there’s Dahl, who was signed by Dallas out of college but didn’t even make it to training camp. He served time on San Francisco’s practice squad, did a stint in Europe, then moved on to Atlanta’s practice squad midway through last season. He was finally activated for the final game of the year, a meaningless win over Seattle.

But the Falcons, short of depth and rebuilding at numerous positions, decided to entrust an entire side of their line to Clabo and Dahl. What looked like desperation turned out to be inspiration.

Perhaps to make up for their physical limitations, the 332-pound Clabo and 308-pound Dahl play harder than anyone on the team — perhaps a little too hard, judging by the number of scrapes they’ve had in both practices and games.

"They bring attitude and they play to the whistle," McClure said. "They make everyone else in that room raise their game up and be nasty and dirty along with them."

Clabo looked almost embarrassed when someone asked if he considers himself a dirty player.

"Dirty? I don’t think so," he said. "Football is a physical game. It’s not dirty to finish and be physical."

Longtime NFL lineman Wayne Gandy, who re-signed with the Falcons after Baker went down, admires the perseverance shown by Clabo and Dahl, especially when it would have been easy to look for another line of work. Gandy believes both linemen are playing with the sort of desperation shown by someone who’s been told over and over he’s not good enough.

"If you ask Tyson, he would probably tell you that he’s not the physically gifted player in the world," Gandy said. "But his mentality and approach to the game is rough, it’s hard. He gets on you and just keeps going and going and going. That wears down people. By the fourth quarter, they get tired if someone is still pushing on them."

Everyone on the Falcons’ line follows the mantra of finding someone to block until the play is over, even if Turner, Jerious Norwood or some other running back has already sped on past them. Defenders, quite naturally, don’t appreciate getting held up when they already feel out of the play.

But Clabo said there’s a reason to keep blocking beyond mindless violence.

"If you can just stay on them the whole time, when Michael or Jerious makes that first guy miss, those other guys aren’t going to be there to make the tackle," he said. "It’s just an attitude. We’re going to finish every play until the whistle, and sometimes" — rolling his eyes and breaking into a grin — "even a little bit after the whistle."

The Falcons (8-5) surely have no complaints about their tactics, especially heading into a must-win game against an NFC South rival.

Tampa Bay was burned for 299 yards rushing in a Monday night loss to Carolina, giving the Panthers (10-3) a one-game lead in the division race over the Buccaneers (9-4). Atlanta is another game back and needs a victory to keep pace with only three weeks left in the regular season.

Look for the Falcons to follow the game plan that worked so well for the Panthers — run straight at the defense, preventing the Bucs from taking advantage of their speed.

The guys up front are eager to get to work.

"The offensive line is a major reason for our success this year," said Roddy White, who leads the NFL in receiving yards. "You know they’re going to do their job. We’ve just got to do ours."