Charlie Batch began the season as the fourth quarterback on the Pittsburgh Steelers depth chart. Even with Ben Roethlisberger being suspended for four games, a roster spot was still not guaranteed for Batch.
Then an injury to Byron Leftwich made Dennis Dixon the starting quarterback and secured Batch's spot on the team for at least the early part of the regular season. In Week 2, Dixon suffered an injury that would lead to a Week 3 start for Batch.
In his Week 3 start, Batch was impressive enough to earn himself a start in Week 4, the last week the Steelers will be without Roethlisberger. Batch's unlikely rise to the top of the depth chart leads one to wonder who the best backups in the NFL today are.
Career Accomplishments: Started 14+ games in a season seven times, 27,293 passing yards, 152 touchdown passes
Starting for such a bad team in Detroit, much of what Jon Kitna has accomplished in his career has been forgotten because of his record as a starter.
Kitna threw for over 4,000 yards twice in his career and completed six seasons with more than 3,000 yards passing. Keep in mind the caliber of teams that Kitna accomplished these feats with in Cincinnati and Detroit.
If Tony Romo were to go down to an injury, the Dallas Cowboys offense would certainly lose a step. However, the team would still be competitive with Kitna at the helm of the passing game.
Career Accomplishments: Threw for nearly 400 yards in his first game as a starter against the eventual Super Bowl champion New Orleans Saints
Despite the questionable decision to let go of Donovan McNabb, the Philadelphia Eagles' quarterback situation remains a positive one. When a team is worrying about whether to start Kevin Kolb or Michael Vick, that team is in a spot that a lot of teams wish they were in.
Although Kolb is only 2-2 as a starter, those two losses have come against solid teams in the Saints and Green Bay Packers.
It almost isn't fair to include Kolb in this discussion since it seems a likelihood that he will be given another chance to be a starter in this league sometime in the future, but Kolb will hold the distinction of being one of the premier back-up quarterbacks in the league in the meantime.
Career Accomplishments: Playoff experience, 17,804 passing yards, 102 touchdown passes
Chad Pennington isn't one of the more flashy quarterbacks on this list, but that is the reason he makes the list. His 102:64 touchdown to interception ratio is light-years ahead of most other backup quarterbacks in the league.
Combine his excellent decision-making with his playoff experience and you have an ideal backup quarterback. Not to mention, Pennington has years of experience in the Miami Dolphins' offensive system to fall back on if he is called upon to start.
Career Accomplishments: Super Bowl appearance, 38,767 passing yards, 193 touchdown passes
With the inconsistency of Vince Young, it is extremely important that the Tennessee Titans have a competent backup at quarterback. The Titans have one of the best in Kerry Collins.
Collins replaced Young in Week 2 of this season against the Steelers and noticeably outperformed Young on that day. When Collins entered that game, all hope of the Titans winning was seemingly non-existent. However, Collins led a touchdown scoring drive which set up an onside kick opportunity that could have made for an epic comeback.
While Young is a much more dynamic player, questions continue to arise as to whether the Titans would be a better team with the seasoned veteran behind center.
Career Accomplishments: 22,814 passing yards, 122 passing touchdowns
After looking at Marc Bulger's stats in his final seasons with the St. Louis Rams, it may seem like a reach to consider him the best backup in the NFL. However, a porous offensive line clearly was at fault for the injuries that plagued Bulger over the past few season and caused his performance to suffer.
In 2006, Bulger appeared to be on his way to becoming one of the top starting quarterbacks in the league when he threw for 4,301 yards and 24 touchdowns. The next season, offensive tackle Orlando Pace was injured in the opening game of the season and Bulger became a sitting duck for pass rushers.
Still only 33 years old, Bulger will have time to heal those bumps and bruises as Joe Flacco's backup. You can be sure that if Flacco is ever unable to play, the Ravens will have complete confidence in Bulger to pick up right where Flacco left off.