I remember when Belfort was around Tank Abott was fighting for the belt. Some fighters wore 1 boxing glove and 1 bare hand and some strikers tapped as soon as they went on their back. Also fighters like Bas, Shamrock and the Gracies were one dimensional, whe a young Belfort came on to the scene, especially with his boxing skills people started to think the fighter were athletes.
Bas was far from one dimensional. He is known as a striker having a background in Muay Thai, Taekwondo etc, but having learnt submissions early on in his career in Pancrase, he finished his career with more submissions than KOs.
I think Bas was a great fighter so are the gracies, but Pancrase wasn't marketed very well often the guy who won was the guy who could stand at the end of a 15 minute round. And in Pancrase you had guys like Smith, Bas, Mezger, Severn, Barnett, Schiltt who no doubt had rounded skills but I had never seen anyone who was good at everything until I saw Belfort.
Personally I woulgn't say Belfort is good at everything. He's is famous for his striking ability and although he has a Black Belt in BBJ he barely uses it. I think Belfort is another example of a rounded fighter that you could group with the guys you mentioned.
The thing with Tank is kind of my point; the time when Vitor was in his prime was probably the lowest point in terms of freakshow-ish type stuff. Not that he himself was, just that before him it was an underground thing amongst a closed community of fighters just their for the sport, then around the time Rorian left the UFC the whole sport went a bit astray for a few years.
Bas learned submissions really quick. I enjoy watching his old Pancrase battles whenever I get the chance. Bas almost guillotined Frank Shamrock in a bout where he kicked Frank's ass from pillar to post. I always wanted to see Frank Shamrock vs Vitor Belfort when they were back in their prime. I remember thinking after watching UFC Ultimate Brazil that they were setting up Belfort vs Shamrock but it never happened. I think Belfort is going to be a worthy challenger for Anderson Silva. Both men have the tools to win.