The 32-year-old's dynamic display against Brazil silenced his doubters and McClaren has also been delighted with the relative absence of the publicity circus that often surrounds the player.
"[Real Madrid coach] Fabio Capello has said he has not looked so fit as he does now for two years.
"Typical David Beckham - he takes adversity and bounces back from it.
"His performances have merited coming back into the team and people now realise why.
"I wanted it to be low key around him, he wanted it and I think it has been key to our preparations this week. He has certainly showed this week in training exactly why he should be a part of it."
Critics still point to the fact that Beckham does not have the burst of pace to get past full-backs, but McClaren insists that is not a pre-requisite.
"All our wide players have got to do is cross the ball into the box, good crosses and good deliveries, and if you have overlapping full-backs and you have people running, David Beckham is one of the best at picking out runners and crossing the ball," said McClaren.