He said that their style of play was too good for the Hammers to cope with on the night, with the variety in their game particularly impressive.
"I thought Sunderland mixed their game up," he said. "They tried to vary their play and stretch us, which they did. We didn't deal with a 40-yard ball and that's how they won the penalty. They weren't just one dimensional.
"It is a very young team and hopefully they'll learn from this quickly. They've been put in the spotlight and it was a harsh lesson."
Sunderland scored their goals through Martin Smith, Rees Greenwood and Duncan Watmore and it was evidence of the quality that they have in their youth ranks at the moment.
Gus Poyet has suggested that their youngsters could break into the first-team in the near future, with Watmore receiving the most praise.
The winger was on the Black Cats' substitutes' bench against Manchester United and Poyet has confirmed in the Chronicle that he will get his Premier League debut soon.
That will be a massive achievement for Watmore, but he certainly appears to be capable of making the step up and his performance last night proved that he is too good to be playing youth football for too much longer.