Cody McCormick was trying to be a good teammate. With McCormick setting a good net-front screen in front of Panthers goalie Jacob Markstrom, Sabres rookie Rasmus Ristolainen put a shot through to score his first career NHL goal. Then things got messy.
McCormick, as many NHL players do, was trying to retrieve the puck for Ristolainen. However, the defenseman he was battling with in front of the net prior to the goal wasn't happy about it. Erik Gudbranson quickly wrapped up McCormick just in front of the net. The two dropped the gloves.
Now, McCormick was making an aggressive move toward the puck, somewhat shoving Gudbranson in the process, so it's probable the Florida blueliner misinterpreted what McCormick was trying to do.
Either way, Ristolainen got that prized puck and he can always remember Cody McCormick was willing to fight someone for it, kind of. The kid might owe McCormick a dinner or something now.