Right now (because I've neglected watching world football for a while) I'd say that Vincent Kompany is the type of defender that's 'world class'. Terry & Cahill do the basics right, they do what you expect of a central defender - doing that alone doesn't make them world class. With the way our system is set up everyone defends, in the end Cahill and Terry don't actually have to do a lot. What makes them very good is that their concentration is continuously high. I'd disagree on your criteria too. With the way the game's moved on now defenders should be judged as footballers just like strikers on the opposite end of the scale, that's why I'd edge Cahill over Terry as a footballer but with Terry's age that's not a fair analysis.