It was when he was defending the hard earned IBF title and before the tournement, somewhere between when he busted and outclassed Simon Brown and once undefeated Glenn Johnson.
He's been on the slide since 2002, the Allen fight in '03 was the first definite proof that he was past his best, obviously he's still good and it's amazing he is still doing what he does, but the idea that he is anywhere near the fighter he was from around '96 - '01 is ridiculous. Prime Hopkins would never lose to Taylor, Calzaghe and Dawson, the only things to ever beat Bernard Hopkins are Roy Jones and old age.