Of course, regardless of definitions of "world class" there are an awful lot who wouldn't include Farrell. He may be inarguable for some (including most of the media), whilst for others you'd he's nothing better than solid at international level. Hell, there are still some out there who still think he's substandard at international level.
However inarguable he may be, you'll get a lot of argument - personally, I go with "decent international" but n better than that, unless all you care about is attitude and kicking from the tee.