By Ken Belson and Kevin Draper, The New York Times The sense of inevitability that the 32 NFL owners tried to project last week when they rushed to New York to approve a proposed 10-year labor agreement has turned into a battle, with faction lines drawn not just between owners and players but also within the players’ union itself. The main stumbling block is a core feature of the proposal — the addition of a 17th regular-season game, which has been met with vocal opposition from many players who say the season is already too long and dangerous.