Todd Haley became a head coach in the NFL largely based on his success as coordinator of the pass-happy Arizona offense during the Cardinals’ surprising run to the Super Bowl two seasons ago.

So how is it then that Haley’s Kansas City Chiefs lead the league in rushing offense entering tomorrow’s game against the St. Louis Rams?

"The vision I have of what I want our team to be is a balanced team," Haley said. "And a team that can run the football when the other team knows you’re going to run it. I think when you can do that, you generally have a good chance to be a good team."

With the exception of last week’s 31-0 pratfall in San Diego, that’s pretty much been the case for Kansas City this season. The Chiefs are averaging 165.4 yards rushing per game, and Haley’s resume notwithstanding, apparently haven’t gotten the memo that the NFL is a passing league.

They have more rushing attempts (445) than anyone in the league. And they are one of only four teams that have run the ball more than they’ve thrown it. (The others: Jacksonville, Oakland and Pittsburgh.)

So to a degree, you can believe Rams coach Steve Spagnuolo when he says he isn’t overly concerned about whether Matt Cassel or Brodie Croyle plays quarterback for KC.

For one, he’s preparing for a system — the scheme run by the Chiefs’ veteran offensive coordinator, Charlie Weis.

"The other thing, that offense begins with the run game, so we’ve got a pretty good focus on that right now," Spagnuolo said.

Jamaal Charles leads the two-headed monster that is the Kansas City backfield.

The third-year pro from Texas is third in the NFL in rushing this season (1,177 yards), trailing only Houston’s Arian Foster (1,330) and Jacksonville’s Maurice Jones-Drew (1,278). What’s most impressive, Charles is averaging 6.1 yards a carry — an unheard of figure in today’s NFL and not far off from Jim Brown’s NFL record of 6.4 yards a carry set in 1963.

"The way I’ve been taught by some of my mentors is you’ve got to develop the players on your roster, specifically the second-, third-, fourth-year players. And Jamaal fell into that category," said Haley, who is part of the Bill Parcells coaching tree. "He clearly made great strides in development in the last half of last year."

Not content with just a talented young back in Charles, the Chiefs signed Thomas Jones, a proven veteran, during the offseason. Jones has 766 yards rushing, giving the Chiefs a chance to have the seventh duo of 1,000-yard rushers in the same season in NFL history.

The speedy Charles is mostly an outside runner but can go north-and-south as well.

Jones is used mainly between the tackles and in short yardage. Jones doesn’t have the big-play ability of Charles but still can get to the corner.

"They’re both very quick," Spagnuolo said. "I think each player can run the whole gamut of their running plays. It’s not like one guy gets a certain type of run scheme (more) than the other."

After a strong first half of the season on run defense, the Rams have slipped some over the past month.

They’ve had trouble containing bounce-out runs to the perimeter and have struggled with misdirection plays and cutback runs, all of which appear to be Chiefs specialties.

"They’ve got some very deceptive running plays where it looks like a reverse, but it’s not a reverse — the back has it," Spagnuolo said. "Then the receiver has it. So we’ve got to be a disciplined football team in defending the run."

A wild card in the mix is rookie Dexter McCluster, a speedy scatback who lines up in the backfield or in the slot as a receiver, and runs reverses and toss sweeps. The Chiefs also use some two-back sets with Charles and Jones out there together. So it’s a lot to chew on for the Rams.

"You have to be really, really good with your eyes," Rams linebacker David Vobora said. "Make sure you’re gap-sound. If you’re off at all, or you let some of their misdirection stuff affect you, that’s where they’ll gash you."