As I said: different era, different positions, longevity that is not comparable at the moment. ozzie's value as an out-of-this-world defensive SS is higher and clearly appreciated more. there's just too much difference to say, let's say last year's Heyward, is at Ozzie-level importance.
I don't thing era or positions matter. 30 runs saved more then the average SS to me is the same as 30 runs saved more then the average RF. 30 runs is 30 runs regardless of where it's coming from. Now obviously SS's get a bump in WAR due to the position dificulty but that's another discussion.
Longevity is an issue when it comes to HOF voting and the like and I guess how long a player needs to play well before he's considered a superstar. I just don't get the notion that average hitters with elite defense can't be considered superstars.