No field of endeavor is more competitive than professional athletics. There are so few roster spots available in pro football that you can rest assured that everybody who makes an NFL roster is an extraordinary athlete (even kickers, in their own way).

NFL players who don't start are aching for an opportunity. Every day of their lives these few individuals who have risen to such lofty heights of athletic achievement study film, scour the play book, hit the weights, run, train … and wait for their chance.

People who bet on sports are always looking for information that will help them find an edge. Of course, sports books are in the business of having first access to this same information. Injuries are a very common variable in football, and they have a profound impact on the public's opinion.

As a handicapper it's a big mistake to place too much emphasis on a player being out due to injury -- even a key player -- and there are several reasons why. For one, the player who is replacing him is going to be well rested, completely healthy, and extremely motivated to overachieve. Starting players get "dinged up" week-to-week and play with little unreported injuries that may in fact impede them from peak performance. The sub getting his chance is fresh and free of these sorts of nagging problems.

An injury to a key player can be a supreme motivational tool. Everybody feels like they have to step up their game because so and so is out. The team plays harder and attends to detail more closely. They feel as though they have fewer margins for error. The coach may even see fit to use the injury as a rallying point, a "win one for the Gipper" kind of thing.

There are many schemes for different situations, different plays that can be called, different game plans that can be employed if necessary. There are coaching maneuvers that can minimize the impact of the injury if necessary. If a quarterback is injured, a coach may choose to run more. Maybe the sub QB can scramble and the starter is more stationary. If an active linebacker is injured the coach may blitz less. If a big running back is injured, the team might run more to the outside with a quicker back. In fact, the injury might result in different looks emerging that are confusing to the other side.

Because of salary realities, the injured player may have been getting all of the playing time because of his high priced contract when in fact there was better talent sitting on the bench. A hungry substitute player's height or size or speed might actually be a better match-up against a particular opponent. And maybe the injured player is out because he aggravated an existing injury that he had been playing with at less than 100 percent, making the team actually stronger with him on the sidelines.

The injury angle in NFL handicapping isn't much of an angle at all because the book is working with the same information that you are and they are going to adjust the line according to the betting. The value in these situations is going to be with the team that has the injury. The less sophisticated bettors will over-value its importance and the wise guys will recognize this and pounce.

Conversely, sometimes an injured player will return to action, and that will cause the line to shift in his team's favor. This is very often a false move that we need to capitalize on, especially if the team has been holding their own in his absence. The team may have settled into the new dynamic and be a little out of synch when the starter returns, and the player himself may be a little bit tentative or rusty.

Injuries are a handicapping factor in football, and they will impact the betting line. But make sure you look beneath the surface, because that's where you'll find the value.