I don't think the skill level so much has dropped, rather the gap between good players and average players has widened. The average player can only commit a certain amount of time a day, whereas the good players have sitters / co-players which greatly enhances their size and ability to grow. For example, look at world 41, the gap there has been extroadinary there has been monumental. From the earliest stages of world 41, there have 6-7 tribes with less then 35 members in the top 20 and 2-3 tribes with less then 20 (some even had 7). And now there are several tribes with 4 members or so in the top 20, etc.. Anyway, since .co.uk isn't as old as .net it makes sense that there are fewer tribes like this in the top 20. But I think it goes to show that the amount of good players has increased and their gap over the average player has only widened.
What this really means, is that eventually, worlds will exist where no family tribes are present. Simply because family tribes will never make it into the top 20 because of the amount of skilled players in the top 20 tribes that create such huge leads over the rest of the pack.
Eitherway, in my opinion, this is a good thing.
