The vagueness of the system is that once you've awarded the penalty, he's got the perception that it's a reckless challenge and therefore a second yellow card.
The timing of it means he catches the top of the ball and followed through.
West Ham, meanwhile, have scored in 13 of their 16 league matches this season with David Moyes' side boasting goals from all over the pitch; 12 different players have netted in the top flight during the current campaign.