FA chief exec Martin Glenn has questioned the mental strength of England's stars.
Speaking at the Leaders in Football conference, the FA chief accused this country's elite footballers of being soft when they are forced to leave their home comforts behind.
"We know that we have not been leading edge in terms of psychological support for that senior team," said Glenn.
"England players do not travel well. They do not tend to play abroad, their familiarity with international camps is not that great.
"And so we know there is a brittleness in unfamiliar circumstances which we have to deal with.
"Sam (Allardyce), in fairness, took that mantle on and Gareth has taken it on too. That is not something that you wish for overnight. You have to work at it."