If ever there was a moment that encapsulated Jan Vertonghen’s apparent decline, it came midway through the second half against Middlesbrough on Sunday.



Having won the ball back, Vertonghen found himself in possession on the halfway line only to give the ball away with a weak pass. Middlesbrough were able to advance on the Tottenham Hotspur defence, while Vertonghen — seemingly lacking either the energy or inclination to retreat — stayed pretty much where he was.



When Tottenham regained the ball, Christian Eriksen looked up and, seeing a white shirt in space, hooked a pass into the opposition half that the Belgium international should have collected.



Instead, despite having a few yards’ head-start, Vertonghen, who turns 33 in April, could barely run for the ball as Middlesbrough defender Paddy McNair came across and cleared it unchallenged.



A disbelieving Vertonghen put his hands on his head and looked skywards. It was one of...