As has been observed, he's just not been the same since he rushed back from that ankle injury in April, as he was busting a gut to get the Golden Boot for the season. If that was never given a chance to properly heal before going into the World Cup, then its not a case of "toughening up", its just flat-out fatigue, wear and tear.
If it’s a niggling ankle injury then that is different. Generally tired ? Not having it.