If a horse is a 159 horse going into a race, and then a 159 horse again within three races after it (beaten all three times), then it has to be questionable whether he ever ran to 169 in that single, anomalous race in between. I agree that most horses will run to their best in a CH, but they tend not to run 10lbs better than anything they've ever done before or since.
Binocular for me was high-160's at best. Certainly that CH effort in no way merited a 170+ rating, which should be reserved for exceptional performances only, and beating the rags he did, wasn't anything remotely like an exceptional performance. It was clearly very good - like a lot of his performances were when he was on a going day - but that Champion Hurdle and his best form generally, was never exceptional.