The A's went 35-27 against above .500 teams including notably, 8-11 against Houston (this is actually an interesting mark because of how freaking good Houston is), 4-2 vs the Yankees, and 4-3 vs the team they're facing in the WC tonight (although they lost the run differential battle).
I totally wouldn't discount them. They definitely completely snuck up again this year though. They started off badly and then I'm looking up near the all star break, and here we go again with another team that stumbled out of the gate then got hot.
They also, as all of the good AL teams did, took mad advantage of some absolutely awful AL teams. Because of that factor I would say it's close between them and Washington.
The Rays did it differently, so I think it's not surprising if people think they're better. They started off very hot before going into a slide, and after a slow start by the Yankees, the Yankees went on a absolutely unreal run. Morton could get them to the ALDS though. I say the A's win the game but either outcome wouldn't surprise me.
Neither deserve to face Houston lol, but I think the A's can give them a fight. They will lose in typical A's fashion though if it is them in the ALDS.