I don't think any captain with less than one minute of observing what is happening out of sleep could figure out why they are descending 10,000 fpm with the nose up. We normally have competent copilots so don't think this can happen.
Agreed...whilst I agree his handover prior to leaving the flight deck perhaps wasn't the best I think it's a tough ask to expect him to walk onto the flight deck having perhaps been asleep seconds earlier and immediately assimilate all that had gone before (and yes, it is certainly possible to be asleep within 9 minutes of leaving the Flight Deck; been there, seen it, done.... ZZZZZZ).