In his prime, I do not think Phil Ivey was overrated at all. However, at this point I do not subscribe to the idea of any 'greatest player of all time' (with perhaps one exception, Stu Ungar).
Poker has always evolved but that evolution has accelerated at a phenomenal rate in the last decade or so. Few if any players who peaked twenty years ago remain consistently competitive against the current younger wizards.
So, from one viewpoint I would not presently place the likes of Ivey (or Negreanu etc.) even close to top fifty in the world. However, that does not mean they could not compete, place of even win in a highly ranked tournament. They have a fundamental skill set after years of countless
hands against top flite opposition coupled with a very high level intuitive game.
Further, I believe if the likes of Ivey (or Negreanu etc.) were so inclined to study in the manner younger players now do, conducting endless sessions with solver outcomes, they could climb back to high level consistency. But, it is fairly obvious after years of playing and many millions won, they do not feel so inclined.
Fair enough. I presume Ivey is intelligent enough to be satisfied with being unquestionably the worlds best for an extended period even if that period is slowly retreating in the rear window.