What was the reason for the grievance?
The criteria for the grievance is...
1: The player in question must have performed "unadmirably" in the first four weeks of his tenure with team A.
2: Team B must have traded the player to team A within the current season.
3: The player much be non-compliant with organization by means of conduct detrimental to the team, drug problems, or injury.
Team "B" would be the Patriots, team A would be the Vikings. The third part comes from his recent fines for not complying with the media policy. Any fine for off the field incidents is considered conduct detrimental to the team. The second part obviously happened. The first part is the only part in question, since "unadmirably" is subjective (and, apparently, not a real word. Way to go NFL rule book!). The Vikings are probably hoping that play he gave up on towards the end of Sundays game will help convince the league that he wasn't playing hard, and it helps them that it just so happened to be against the Pats.