The one exception is if a player did things that directly hurt the team or his teammates. Those are the type of things that concern players much more than the harm or negative attention that delinquent players bring on themselves. The stuff off the field, like domestic abuse or steroids, would not affect most players in the locker room other than frustration if the player misses games as a result.
I played on teams with guys who were blatant with their infidelity in the hotel the night before games. I find that behavior disgusting and reprehensible, but ultimately it didn't really affect my life. I, like most players, would feel a lot more animosity and frustration with a player who refused to play through a small injury or who cost us a victory because he made a series of mental mistakes in the game due to his lack of preparation. Win and losses had a direct impact on my life, especially if they led to a coaching change at some point, whereas a guy choosing to be unfaithful did not.
There is a school of thought that Vick's mere presence on a roster, and the media frenzy that would follow, would be enough to cause a distraction for a team that could otherwise focus on the task at hand. The argument can be made that as long as a player is answering questions about Vick, he is not working on his craft. Some will point to the New York Giants' faltering down the stretch of the 2008 season after
NFL players are conditioned to have stock answers ready for the tough questions they know are going to be asked. They have a solid understanding of what to say and what not to say. The likelihood of a player speaking out against the signing or Vick's reinstatement is less than zero because once the transaction has been made and the front office has gone in that direction, the player really has no choice but to support it. At that point a player would be foolish to speak out against it, even if he did have negative feelings. Taking a stance against management's decision would only serve to adversely affect that individual's career, and nobody is going to take that chance.
There are players in Buffalo who are less than thrilled about the acquisition of