I'll start
Gambit
There's nothing to "trust." It's based on elo and, therefore, based on results. If you like basing everything on opinion, then, sure, it isn't ideal. But if you like facts then ranking by elo is great. I'm a facts guy.
Maybe the way you should look at the ranking is that they are a step behind current form, because obviously they cannot predict the future. Use the rankings to give you an understanding of where the teams are based on their past results. Again, there's nothing to "trust," lol.