That's because the blue-liner was nailed on what appeared to be a hit from behind by Montreal Canadiens forward Max Pacioretty at 4:28 of the first period.
Boychuk was down on the ice for several minutes, in visible pain while trainers attended to him before removing him on a stretcher and taking him to a hospital. General manager Peter Chiarelli said in a statement Boychuk was "able to demonstrate movement in all his extremities."
The nature or severity of the injury wasn't immediately clear, and Pacioretty was penalized for boarding on the play.
Watch the incident in the video above. Do you think Pacioretty's hit was clean? Why or why not?