A defiant Erik ten Hag has warned Manchester United what they’ll be missing if the club decides to sack him after winning the FA Cup. Manchester United are basking in the glow of an unlikely FA Cup final triumph after they defeated rivals Manchester City 2-1 at Wembley. It was no fluke, either, as, despite Pep Guardiola’s claim to the opposite, United were the better side and were fully deserving of their victory. Alejandro Garnacho pounced on a defensive mishap to tap into an empty net for the opener before Kobbie Mainoo finished off a fine move to double the lead. City got one back late on t…