By Dan Marsh The Key Match Incidents panel (KMI) have ruled that Kai Havertz should have been shown a second yellow card prior to his winning goal for Arsenal against Brentford earlier this month. Havertz, 24, had been cautioned following an elbow on Bees defender Kristoffer Ajer before he went down under a challenge from Nathan Collins in the 65th minute of Arsenal’s dramatic 2-1 victory at the Emirates Stadium. Replays at the time showed there was minimal contact between the Germany forward and Collins, with referee Rob Jones failing to take action. The former Chelsea and Bayer Leverkusen st…