They’re No. 2

When San Francisco quarterback Alex Smith looks over his shoulder this season, he’ll probably see some 320-pound beast looking to separate him from his sensibilities. But when Smith looked over his shoulder this summer, he saw something far more comforting: Trent Dilfer, his good buddy and backup, who acts as a second set of eyes and an unofficial position coach.

Dilfer, 34, who won a Super Bowl with the Baltimore Ravens in 2000, is what many people would consider the ideal backup. He’s smart, competitive, experienced ... and he knows his place. He can live with carrying a clipboard on the sideline, knowing at any moment he might have to step in and take over the offense.

“A guy like that is so rare in this world,” Smith said. “With so many people, it’s an all-about-me attitude, kind of a cutthroat environment. Here’s a guy where it’s the exact opposite. It’s all about the team.”

Backup quarterbacks often are called the most popular athlete in town -- mostly because when things get bumpy for the starter, fans scream for his understudy.

At some point, for some reason, they usually get him.

The only starting quarterback to throw every pass for his NFL team last season was Kansas City’s Trent Green. Drew Bledsoe was the only quarterback Dallas used, same goes for Eli Manning with the New York Giants, but both of those teams called on receivers or running backs to throw from time to time. The New York Jets cycled through five quarterbacks: Brooks Bollinger, Vinny Testaverde, Chad Pennington, Jay Fiedler and Kliff Kingsbury.

The quintessential backup: Matt Cassel, who backs up Tom Brady for New England.

Cassel wasn’t even the starter at USC. He backed up Carson Palmer, then Matt Leinart.

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(BEGIN TEXT OF INFOBOX)

Rating the Backup Quarterbacks / Sam Farmer

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TEAM: Atlanta

STARTER: Michael Vick

MAIN BACKUP: Matt Schaub

Schaub, who holds nearly every passing record at Virginia, is good enough to start for several NFL teams.

-

TEAM: Chicago

STARTER: Rex Grossman

MAIN BACKUP: Brian Griese

The Bears made the mistake of passing on some quality backups last season. Griese has a 39-33 record as a starter.

-

TEAM: Jacksonville

STARTER: Byron Leftwich

MAIN BACKUP: David Garrard

At 6 feet 2, Garrard is a tad small, but he was 4-1 as a starter last season.

-

TEAM: San Francisco

STARTER: Alex Smith

MAIN BACKUP: Trent Dilfer

Dilfer’s Super Bowl ring counts for something, even though his Baltimore team won with defense.

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TEAM: Arizona

STARTER: Kurt Warner

MAIN BACKUP: Matt Leinart

Leinart looks as poised and comfortable as the experts said he’d be. If the Cardinals can protect him, there shouldn’t be much of a drop-off if he’s needed.

-

TEAM: Baltimore

STARTER: Steve McNair

MAIN BACKUP: Kyle Boller

Boller completed a career-high 58.4% of his passes last season, despite sitting out seven games because of a toe injury.

-

TEAM: Carolina

STARTER: Jake Delhomme

MAIN BACKUP: Chris Weinke

Weinke, who recently signed a three-year deal, knows the Panthers’ offense as well as anyone.

-

TEAM: Cincinnati

STARTER: Carson Palmer

MAIN BACKUP: Anthony Wright

Wright has started 19 games in seven seasons and occasionally has looked very good.

-

TEAM: Dallas

STARTER: Drew Bledsoe

MAIN BACKUP: Tony Romo

Romo hasn’t attempted a pass in three seasons, but he showed this summer that he’s more than adequate in a reserve role.

-

TEAM: Indianapolis

STARTER: Peyton Manning

MAIN BACKUP: Jim Sorgi

Sorgi has looked good when he has gotten a chance to play. But that’s almost never.

-

TEAM: Miami

STARTER: Daunte Culpepper

MAIN BACKUP: Joey Harrington

Things didn’t work out for Harrington in Detroit, but he has the credentials to be a spot-duty NFL player.

-

TEAM: Philadelphia

STARTER: Donovan McNabb

MAIN BACKUP: Jeff Garcia

Once a Pro Bowl player, Garcia has fallen off the map. But he’s a capable understudy.

-

TEAM: Pittsburgh

STARTER: Ben Roethlisberger

MAIN BACKUP: Charlie Batch

Batch won’t wow anyone, but he has been an NFL starter and is generally steady under pressure.

-

TEAM: St. Louis

STARTER: Marc Bulger

MAIN BACKUP: Gus Frerotte

Not only does Frerotte have a ton of experience, the former Dolphins starter knows Coach Scott Linehan’s system.

-

TEAM: Tennessee

STARTER: Billy Volek

MAIN BACKUP: Vince Young

Volek is destined to become Young’s backup at some point, and he did a very good job previously behind McNair.

**

TEAM: Buffalo

STARTER: J.P. Losman

MAIN BACKUP: Kelly Holcomb

Both quarterbacks are good enough to deserve a chance, and bad enough to cause Bills fans to scream, “Put in the other guy!”

-

TEAM: Denver

STARTER: Jake Plummer

MAIN BACKUP: Jay Cutler

Cutler will be good down the line. The Broncos are hoping they don’t have to put him in too soon.

-

TEAM: Detroit

STARTER: Jon Kitna

MAIN BACKUP: Josh McCown

In the last two seasons with Arizona, McCown was replaced as a starter three times. Kitna is better suited to be a backup.

-

TEAM: Green Bay

STARTER: Brett Favre

MAIN BACKUP: Aaron Rodgers

Once viewed as the heir apparent to a legend, Rodgers was so-so in limited duty last season.

-

TEAM: Kansas City

STARTER: Trent Green

MAIN BACKUP: Damon Huard

Green threw every pass for the Chiefs last season, and Kansas City has to be praying for an encore.

-

TEAM: New England

STARTER: Tom Brady

MAIN BACKUP: Matt Cassel

Cassel has looked good this summer. There is something to say, though, for NFL regular-season experience. Or even college experience.

-

TEAM: New York Giants

STARTER: Eli Manning

MAIN BACKUP: Tim Hasselbeck

Aside from a brief stint in Washington in 2003, Hasselbeck has next to no experience.

-

TEAM: New York Jets

STARTER: Chad Pennington

MAIN BACKUP: Patrick Ramsey

Pennington is injury prone and Ramsey didn’t win over the Redskins.

-

TEAM: New Orleans

STARTER: Drew Brees

MAIN BACKUP: Jamie Martin

The Saints have several good players on offense. Martin is not one of them, although he was 4-1 last season as a starter in St. Louis.

-

TEAM: Oakland

STARTER: Aaron Brooks

MAIN BACKUP: Marcus Tuiasosopo

Exactly what the Raiders want in a quarterback is unclear. Tuiasosopo is a stopgap; Andrew Walter is a more conventional choice.

-

TEAM: Seattle

STARTER: Matt Hasselbeck

MAIN BACKUP: Seneca Wallace

Wallace doesn’t have much experience at quarterback, but as a receiver he might have the best hands on the team.

-

TEAM: Tampa Bay

STARTER: Chris Simms

MAIN BACKUP: Tim Rattay

Jon Gruden’s reputation for molding quarterbacks will be put to the test with Rattay, who was mediocre at best with the 49ers.

TEAM: Washington

STARTER: Mark Brunell

MAIN BACKUP: Todd Collins

They have a journeyman backup, but if Brunell gets hurt the Redskins will have to do some shopping.

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TEAM: Cleveland

STARTER: Charlie Frye

MAIN BACKUP: Ken Dorsey

The Browns should have kept Dilfer instead of backing up young Frye with a three-year pro with 10 career starts.

-

TEAM: Houston

STARTER: David Carr

MAIN BACKUP: Sage Rosenfels

With the beating Carr takes, it’s not illogical to think he could wind up on the sideline. Rosenfels is not the answer.

-

TEAM: Minnesota

STARTER: Brad Johnson

MAIN BACKUP: Mike McMahon

McMahon is not very accurate, meaning the Vikings are hurting if the 38-year-old Johnson takes a tumble.

-

TEAM: San Diego

STARTER: Philip Rivers

MAIN BACKUP: Charlie Whitehurst

It’s risky backing up a first-year starter with a rookie, but the Chargers were comfortable enough with Whitehurst to cut A.J. Feeley.