NFL teams treat the game as a business, and they generally conduct their negotiations with their players in such a manner. It only behooves the players to do the same, which is one of the reasons that there can be a stats obsession at times—because numbers get players paid, through earned bonuses and in lucrative free agent contracts.
One can easily argue that that is to the detriment of the game; statistics, though, will never tell the full story. For example, the fact that second-year edge rusher Alex Highsmith only has one and a half sacks on the season would suggest to you that he’s an ineffective pass rusher, but watching the tape would tell you another story.