Injuries to quarterbacks in the NFL have become so commonplace that it is almost a bigger story if a starter isn't hurt than it is if he has to miss a game or more. Off the top of my head, Miami, Minnesota, the Jets, Baltimore, St. Louis, Carolina, Arizona, Buffalo, San Francisco, and Oakland have all had their starter miss time because of injuries, and we are only heading into Week 6. Those problems have led some teams to make some bizarre but necessary signings (Tim Rattay? Vinny Testaverde?!??).

When the public hears the words 'quarterback injury' it often causes them to panic and throw their money blindly on the team that still has their starter behind center. Sometimes that's the right move, but more often it is a choice made without considering the facts in their entirety, and those choices rarely work out well. It could very well be the case that a quarterback change will have little impact, or will even give the team a better chance of winning. Before you make a rash decision about a game based on a quarterback change, then, you need to really think about what the injury means. Here are some things to consider to get you started:

1. How good is the starter? This is the most important place to start, but many people seem to miss it. Buffalo lost J.P. Losman, for example, but so what? The offense was totally inept with him in place, so what's the downside of a new starter? Trent Edwards could have been worse, but it's not like there was anything to ruin in the first place. Losing a top starter like Tom Brady or Peyton Manning, and having him replaced by an unseasoned and obviously inferior option, is a problem for a team. Having a questionable and barely effective starter replaced by another question is not likely worthy of changing the decision on the game you would otherwise make. At least half of the teams that have had injured starters this year fall into the latter category.

2. How is the public acting, and the line reacting? By looking at the line movement and the percentage of bets placed on each team you can quickly get a sense of how the public is reacting to a move and, more importantly, how the books feel about the public action. If a line is swinging wildly then the injury was not sufficiently compensated for in the line when it was set, and the books may have been caught off guard. That could make the game more interesting. If the line isn't moving despite overwhelming public support for one team then the books have compensated for the injury, and the line may not be soft enough to make it worth your attention.

3. What kind of an offensive system does the team use? If a team is centered heavily around the pass then it will be hurt by a quarterback injury much more than one that runs as a first choice. Green Bay would feel more of an impact if they lost Brett Favre (No. 1 passing, No. 31 rushing) than Oakland did when they had to shuffle starters (No. 1 rushing, No. 29 passing).

4. Who is the backup? When Arizona lost Matt Leinart for the season you could argue that Kurt Warner was at least a lateral move and maybe, at this point, an improvement. Jake Delhomme has been so average of late that David Carr is a fine substitute in Carolina. In those cases a loss of a starter is likely worth only a passing glance. Gus Frerotte is not as good as Marc Bulger is when he is healthy, but he is a veteran who has seen and done everything, and the Rams have been badly struggling, so the change is again not worth panicking. In many cases, the backup is more than adequate as a replacement, and the public reaction may create an opportunity to find value by backing the new starter.

5. Who are they playing? The success of the quarterback in a given game has as much to do with the play of the defense as it does with anything he does. A backup who hasn't seen a lot of recent game action will be rusty and may be more affected by the defense. That means that considering the defense is especially important. Is the new quarterback in a position to succeed? You will also want to look at the style of the quarterback and the relative strengths of the defense. It's conceivable that a team could actually benefit from a quarterback change if they are facing a strong pass defense and a weaker run defense, and a pocket quarterback is being replaced by one who can effectively tuck and run.

6. What would the line be with the starter playing? The best thing you can do in situations with an injured starter is to consider what you think a fair line would be if the starter were healthy and ready to play. By doing that, and then comparing it to what the line is with the new starter in place, you will be able to see if the change in line makes sense, and if you can easily explain where the changes come from. If you can't then this is an excellent way to spot value.