Piet, based on your perfect seeding system, Ghana is ranked number 5 in the world. I think we all know that is not true. Ghana won only 2 matches at the World Cup - 1-0 against Serbia, and 2-1 after extra time against USA. Herein lies the problem of 'previous performance'. Ghana were not the 5th best team at the World Cup. Portugal would be 13th - but in my opinion, they were better than Ghana at the World Cup. The difference between Portugal and Ghana: Portugal were drawn against Spain in the Round of 16, Ghana were drawn against USA. That's the only reason Ghana went further than Portugal at the World Cup.
I would still rank Netherlands higher than Belgium. Belgium is probably not even Top 10 yet.
My top 16 (based on rankings taking into account ALL matches) would be:
Based on the previous World Cup, the top 16 are:
11. South Korea
I think I know which system would be the best for seeding teams. The form of countries changes a lot over 4 years - so it makes no sense to seed them on performances obtained 4 years ago...
Good rankings are the best and fairest way to seed teams. The end.