Dutch defender Heitinga, 26, has been a bit-part player for the Toffees this term despite a starring role in his country's South Africa campaign in the summer.
The former Ajax and Atletico Madrid man has only started four Premier League games but Moyes insists there is no time for egos at Goodison Park.
"There's been disappointment on his part that he didn't start in the team," he said in the Daily Star.
"The reason was that I didn't feel that he had regained his focus from the World Cup.
"You could argue a few players have not got into their form after it.
"But I think he needed to regain his focus. In a way, I think he probably accepted that
"He's maybe realising now there's big competition for places here - and it doesn't matter if you play in the World Cup final for Holland.
"If you don't play that well, we can't start you.
"He may not accept it, but he's the type of character that knows what's right in this football world."
Heitinga moved to Merseyside in August last year for £6million and was a key player for the club last season.