This shorthanded goal isn't possible without some effort by the Bruins' Brad Marchand, but what sloppy defense from the Kings.
With the Bruins on a penalty kill, Marchand takes the puck by himself into the Kings' zone, getting around Drew Doughty, the last line of defense. Doughty drops his stick in the process and screws up the breakaway, but thanks to Jeff Carter's lazy clear—and Marchand's fortunate position—the Bruin gets the rebound, maneuvers around Anze Kopitar and puts it in for a 1-0 lead.
Take a look at where the Kings are after the original shot. Three of them seem to be having a chat with goalie Jonathan Quick! Were they trying to figure out who should apply the slightest pressure to the one guy threatening to score?
Thanks to Marchand's fourth shortie of the season, most in the league, Boston won, 3-2.