The franchise had every reason to assume Tom Brady would make it through another season unscathed. He hadn't missed a start since assuming the role three games into the 2001 campaign. Brady was adept at avoiding big hits thanks to outstanding pocket presence and an offensive line that sent three members to last season's Pro Bowl.

All that changed last Sunday when Brady suffered a season-ending knee injury against Kansas City in his 2008 debut.

Brady's loss does more than affect the NFL's competitive balance. It will force teams to evaluate their own backup situations and preparedness should the same happen to them.

FOXSports.com is here to help. We've divided second-string quarterbacks into four categories — all of which reflect different organizational philosophies about how the position should be addressed.

Unproven apprentices

New England (Matt Cassel), Green Bay (Matt Flynn), Detroit (Dan Orlovsky), Cincinnati (Ryan Fitzpatrick), Baltimore (Troy Smith) and Indianapolis (Jim Sorgi).

Brady and Peyton Manning have the NFL's longest starting streaks behind Brett Favre. They are two future Hall of Fame inductees still in their prime.

Accordingly, Brady and Manning command two of the league's highest salaries.

Wanting to spend money at other positions under the salary cap this offseason, New England and Indianapolis eschewed allocating as much as $3 million annually to established backups like Washington and Jacksonville did with Todd Collins and Cleo Lemon, respectively. Instead, the Patriots and Colts continued to stick with late-round draft choices Cassel (2005) and Sorgi (2004) as less costly developmental projects.

They aren't the only clubs rolling the dice.

Detroit and Green Bay have second- and third-stringers who have never started an NFL game. Fitzpatrick hasn't played since 2005 -- and that was with St. Louis, not Cincinnati.

The Bengals, Lions and Packers believe grooming passers in their own systems is wiser and more financially prudent than pursuing pricier veterans. It's what the Patriots successfully did with Brady -- a 2000 sixth-round pick who had a year of seasoning before his first start -- and will try doing with rookie Kevin O'Connell.

As for Baltimore, rookie Joe Flacco was rushed into the starting lineup because of preseason ailments suffered by Smith (severe tonsillitis) and incumbent Kyle Boller (shoulder/season-ending). The Ravens have signed journeyman Todd Bouman but Flacco and Smith are expected to occupy the top depth-chart spots through 2008.

Grizzled veterans

Dallas (Brad Johnson), Jacksonville (Lemon), Washington (Todd Collins), Minnesota (Gus Frerotte), Tampa Bay (Brian Griese), New Orleans (Mark Brunell), Atlanta (Chris Redman), San Francisco (Shaun Hill), St. Louis (Trent Green), Tennessee (Kerry Collins), San Diego (Billy Volek), Kansas City (Damon Huard) and Pittsburgh (Byron Lefwtich).

Backups for these teams all have at least six years of NFL experience. Leftwich, Lemon and Hill are the only quarterbacks under the age of 30. The average age of the other 10 reserves is 35.

Minnesota, Kansas City and Atlanta have veterans who help tutor less-experienced starters. Other graybeards like Volek and Todd Collins had their moments in 2007 when pressed into action. Huard and Kerry Collins already will start this Sunday because of opening-game injuries, while Griese gets the nod if Jeff Garcia (ankle) can't play.

Age and diminished skills make it questionable whether many of these quarterbacks can thrive over the long haul. That's why most of this group is firmly entrenched as reserves for the rest of their NFL careers.

Once-promising youngsters

Arizona (Matt Leinart), Chicago (Rex Grossman), New York Giants (David Carr), Denver (Patrick Ramsey), New York Jets (Kellen Clemens), Buffalo (J.P. Losman), Oakland (Andrew Walter) and Seattle (Charlie Frye).

All of the quarterbacks in this classification were drafted in the first four rounds. That includes five first-round selections in Leinart, Grossman, Carr, Ramsey and Losman.

Leinart is the only backup who may figure into his team's future plans as a starter, although he lost the job to Kurt Warner during the preseason. The others are relegated to reserve roles after failing to capitalize on previous starting opportunities that may never come again.

Waiting in the wings

Philadelphia (Kevin Kolb), Miami (Chad Henne), Cleveland (Brady Quinn), Carolina (Matt Moore) and Houston (Sage Rosenfels).

The Eagles, Dolphins, Browns and Panthers have first- or second-year players being tutored as future starters. At worse, players like Quinn and Kolb could become attractive trade options if Derek Anderson and Donovan McNabb maintain solid grips on their jobs.

The team with the NFL's best backup situation is Houston with Rosenfels slotted behind Matt Schaub. While the two posted almost equal passing statistics last season, Rosenfels was 4-1 as a starter.

Because the Texans made such a huge financial investment in Schaub, Houston didn't open its starting competition this preseason. The Texans also insisted upon a second-round pick as trade compensation for Rosenfels during the offseason. That scared off one strong suitor in Minnesota. The Vikings signed the well-traveled Gus Frerotte after refusing to surrender more than a third-round choice for Tarvaris Jackson's understudy.

Provided he doesn't supplant Schaub in 2008, Rosenfels should return to the trade market during the off-season. Once again, the Texans are expected to drive a hard bargain.

Such demands are understandable. As the Patriots may soon find out, good backup help is hard to find.