Everyone has his own interpretation of WC. From what SAF wrote it seems that he values WC as players who had a knack of dragging teams into victories on their own even though the team may have an off day. Scholes, Giggs (expecially against Juve), Cantona and Ronaldo were all capable of doing that.
I disagree with that interpretation of WC. For starters it punishes defensive players (especially goalkeepers) as they will never be able to drag teams to victory on such circumstances. No matter how good Schmeichel or DDG were/are they won't be scoring goals anytime soon. Which is why you won't see Schmeichel, DDG, VDS, Irwin, Stam, Rio, Vidic and Keane in that list.
In my opinion A WC player is a player who do extremely well week in week out for a long period of time (ie years). If you want to be particularly selective then you'll add the ability to do more then what is written on the tin which would then eliminate specialised players like goal poachers (RVN, Inzaghi, Vieri) or purely defensive midfielders (ex Gattuso or Ince)
If you ask me, SAF had been very disrespectful towards his former players. No manager, not even himself, can win so much with just 4 WC players.