I feel like if a player makes the world team of the year they should automatically be promoted to “World Class”, as far a their class goes. Seems…odd to have Class A players on the best team possible.

The class is determined by weighted skill average + stars. This could mean one of two things, either the world team player skills are not as good as some of the other S players for the same position OR the calculated weighted average for the season is a bit off when compared to real performance. The exact weight of each skill is dynamically updated each season in an attempt to stay relevant.

So each season the importance of each skill changes a bit?

Not in practice (match performance), just in the game formulas to calculate how good a player is, which is in turn used to determine class, estimated value, expected wage…this is a way to try and get the closest approximation possible and keep adjusting.