my definition would be to play at the top level and that must mean international level and in the major competitions which means world cup, European, African or South American championships. And to perform as a star player consistently in those competitions e.g. to be appreciably better than your peers. In that case I was probably wrong to say Mascherano is a world class player good yes but appreciably better than his peers? Probably not.
There is nothing wrong with touching this subject again, however the true answer is down to personal belief. I get what your saying, but when Messi plays for Argentina he does not fit into the category but I would not dispute that he is world class.
