City thumped Feyenoord 4-0 at the De Kuip.
Boskamp stated: "I was shocked.
"On all fronts they were better. Speed, strength, positional play, everything. It was a world difference.
"I think Manchester City did not lose in the first half a single duel. They were always a step faster than us. Afterwards, you can be happy that it remained 0-4."