Hollinger's rankings are no more valid than any informed opinion. They're just arbitrary stats put into a formula, intended to spit out a supposed "unbiased" set of rankings. Whatever.
Personally, in relation to sports, I have very little use for stats. I believe informed, knowledgeable, opinion based analysis is more accurate.
I will say this though, Hollinger is no fool. He is knowledgeable about basketball. On the few occasions when he just gives his opinion, he is generally pretty accurate in his analysis. The problem is, he's just too tied to his "stats" overall.
The main thing I take away from his rankings or "PER, is he's just trying to provide a different point of view, that some readers may be interested in. Basically, it's his way of trying to play to a specific audience that is inclined to find this point of view valid. That, and it creates a highly controversial point of debate, therefore generating more viewership for his employer.