With respect, all you non-pilot guys are over thinking it.
Light plane, Manual thrust,increasing headwind, 4am in the morning, haven't gotten up for a pee in six hours, crappy rosters for months on end, trim a bit too much nose down when the somotogravic hits....... that's it IMHO.
And that's why you want a well rested crew.
People in normal jobs have moments when their brain doesn't process information well often, and nothing happens. People driving cars have moments when their brain doesn't process information well and most of the time they get away with it, sometimes they crash, rarely is it headline news.
We know this crew was capable of flying a go around because they did one two hours earlier. When this comes back that there was no aircraft malfunction I hope we all acknowledge that being well rested and in good mental shape is critical to flight safety and crew rostering should be regulated to ensure that profits don't get in the way of the paying passengers expectation that they will survive the flight.