The FIFA rankings are generally a lot better indication of a teams ability than a lot of people give them credit for.
I imagine it’s tricky to weight Asian teams results though as they rarely play anybody outside of their own federation in between World Cups.
Iran for example have played only one European team since the last World Cup. They beat Bosnia. They’re also only played one South American side and beat Uruguay. In that last World Cup they beat Morocco, drew with Portugal and lost narrowly, 1-0 to Spain.
Anybody assuming they’ll be shit, just because Iran sound like a country that will be shit, might be in for a bit of a surprise.