In wrestling, to be the best, you need to be the best every single night - whether you're in the ring with an opponent of equal standing or an upstart rookie taking their tentative first steps under the bright WWE lights.
Dave Meltzer and the Wrestling Observer Newsletter's star ratings are only subjective, but they are a good measure of who has had the best match of the night, and - when you add them up for combined, aggregate totals - who is having the best matches over the course of a year.
This, of course, is not a definitive way of ranking wrestlers, since some will inevitably contest more matches - and, importantly, longer matches - than others. There're also things like injury to take into account, making it less about who is the most talented than who is having the best (and, in some cases, most bad luck-free) year.
Bear in mind, too, that these aggregate ratings are only comprised of matches graded at three stars or more (outside of pay-per-views, those ranked lower than this are often not recorded). It also won't include matches from Hell in a Cell, which were not published at the time of writing.