What history showed us in Wilt was that for all of his era dominance, mentally he could not put it together to win like most of us felt he should of. Hell, for how massive his individual accomplishments are, the tall tales of past teamates, one just learning the game would probably get 11 rings & Russell mixed up with Wilt, when in fact the RPOY & Top 100 have made me respect Russell and what he did for the game so much more than Wilt.
But the truth is, for all his glory & accomplishments, when compared to the rest of the immortal 6, Wilt should be at the bottom and now should be replaced by Shaq. For a man, who didn't have weight problems as even Mr. Charlie Rosen would quickly point out, he never figured out how to be a winner to match that dominance his was given.
For a man who was so much faster than Shaq, he certainly couldn't truly utilize this distinct advantage consistently over his career when it mattered most and when his team needed him to do so most. And good old Charlie propping up his favorite era of basketball, as he himself is a 6'9 big, but I must admit I am not impressed.
Plain and simple, from an offensive dominance perspective when compared to O'Neal, Wilt's offensive game was not as powerful and I dare use the word 'softer' than what we witnessed from Diesel. That is not to say his offence wasn't effective or dominate during his time because it certainly was but seeing as we really only have the two of them to really compare (as top gladiators), since the inception of the nba, only against O'Neal do I dare say this.
From a skill perspective Wilt wasn't offensively skilled like Hakeem at any point in his career and defensively as other have pointed out Russell's impact was greater. Shaq wasn't as offensively skilled as Hakeem either but his style of play didn't need him to be and in fact would have taken more away from his game than added to it and we know Shaq wasn't a defensive anchor like Russell.
Here's what we know, Russell defeated Wilt many many times. Why? Russell could rattle Wilt and make him feel that for all his great gifts, dominance, it wouldn't matter against Bill and he would show no signs of it. This is Wilt's flaw and why he needs to now be removed from the top 6 and put somewhere in the top 10.
You watched a 3rd year Shaq go toe to toe with a prime Hakeem who one could argue with his offensive skill was just as deadly as Russell himself as a balanced player. Shaq showed no fear and played him back and forth till the end. Now replace Russell with O'Neal, and Shaq just waiting to steam roll over Wilt as he wants to prove who is most dominant. Changing many aspects of Wilt's game as Wilt needs to adjust to someone of equal to larger size. Mentally getting weaker as he is like 'damn' I can't hold position on him etc.
Where I am going here, Shaq has never lacked confidence and the instinct to want to murder anyone within 5 feet of the basket and had the offensive & defensive tools to dominate anyone anytime he wanted. Shaq's offensive game was better suited for Wilt's era anyway and I would really love to see who would forearm Shaq to the ground for dunking and breaking all the basket's in the gym

If Russell, defensively, could slow Wilt down just enough that mentally Wilt already lost than Wilt facing someone who could go toe to toe point for point, size for size, block for block may have caused him to reconsider track & field

Like Shaq, Wilt really had no one to truly challenge him or his ability to where Wilt would admit. We already know Wilt thinks Russell when compared to himself was a peasant.
Shaq wouldn't need 22.9 rebounds per game or lead the league in blocks or assists because Shaq's game causes the 'Russell Effect' if you will on most everyone that plays him. I only wished Russell was a little bigger and had a more offensive post game consistently against Wilt. I could only imagine what that would have done to bring out his insecurities even more.
At some point in our lives, all of us have come up against someone who was intimidating, could answer our best play or move and we all know how we felt. Maybe some of us were mentally stronger, although you couldn't always say that even with that the outcome was positive. Now picture that same scenario without the mental toughness.......