...so are we doubting Haye's attributes at Heavy

Personally I think his chin looked a little weak due to weight drain. You try loosing 2 stone in 10 weeks of training to fight the biggest fight of your career to date.
He will have a good chin at Heavy and his stamina will be fine. It has come a long way since Thompson and IMO he was as strong in the 6th and 7th as he was in the 1st.

He did a good job!