Matthew Tkachuk has been a star of the United States, but he may have suffered an injury at the 4 Nations Face-Off. The USA star appeared to get injured at some point in the third period of the round-robin game against Canada at the 4 Nations Face-Off. Tkachuk took a few shifts in the early parts of the frame, but he did not appear the final 12 minutes of the game. Tkachuk has been stellar for...