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The NFL currently is on the ropes after a the release of a Congressional report concluding that the league tried to exert undue influence over a National Institutes of Health study regarding concussions. And the NFL Players Association is trying to punch the league through.

“This is why the NFLPA refused to be a part of any study with the NFL,” NFLPA president and Bengals offensive lineman Eric Winston said on Twitter. “They cannot be trusted to do the right thing when it involves players.”

Separately, NFLPA executive director DeMaurice Smith said via Twitter that “this is another example of a league that is out of control.”

The strong reaction of the NFLPA is stunning but not surprising. The union has faced fights at every turn with the league office over the past few years, with trust between the two sides consistently eroding. Earlier this year, a largely-overlooked arbitration ruling concluded that the NFL diverted money that should have been included within the salary-cap calculations into a made-up category of exemptions for stadium renovations. Some with the union regarded the development as the NFL stealing money from the players.

It’s all pointing to potentially acrimonious labor negotiations in five years, with the NFLPA and the rank and file perhaps more willing to miss game checks than it was in 2011.