A mental block and that formation
This was a Tottenham Hotspur team that contained a World Cup winner, a Champions League winner and a number of Champions League finalists, a Copa America winner, title winners in various leagues and players who had taken to the field in a European Championship final at Wembley just over a year ago.
Yet put them out on the pitch at the Emirates Stadium, or even Stamford Bridge, and that goes out the window. Give them the Etihad or even Anfield pitch and they often won't wilt in the face of pressure but there's something about heading across London to those two grounds that makes any past experience and success dissolve.