You're exactly right- I was just compelled to mention it because I've seen Bute's chin called into question since the Andrade fight, which I think is a bit crazy given that he's faced other guys with a punch without his chin letting him down (Berrio, Bika, for example). The fatigue was the biggest culprit by the end of that fight.
Berrio has true one-punch KO power and Bika is a considerably harder puncher than Andrade. Both have clocked Bute flush on the chin with big shots. Bute was fine. It's not the chin. Bute has a very good chin. It's the fact that Andrade was so much stronger, sapping Bute of all energy in the clinches, and because the workrate and pressure were enormous. Bute's trainer says they did some tests and Bute was suffering from a physiological ailment. He didn't say more. He said that this was responsible for him collapsing physically like that. :good
Lucian Bute has an iron chin. I never saw him wobbled after a shot. Nothing. And it's not because he has a defense ala Mayweather..The guys get hit flush, but he is never hurt. It's a bad thing for the other boxer in 168lbs.