I never saw Russell play but have read a lot about him. I am always amazed when I read someone say that he would be only a marginal player in today's game. That is incredible to me that people, fans even, are that near sighted. So he played 45 years ago? Bird played almost 20 years ago, does that make him less of a player?
I like the person's comment above about how Russ was such a cerebral player. When you combine that ability with his athleticism and killer instinct and you have a very, very special athlete. Bird had two of those three in abundance but was never gifted with Russell's athleticism. It's too bad that defense is so underrated. I guess it's because there are not always stats for it.
I never understood that mentality either.
Granted, today's athlete across all the sports are bigger, faster, and stronger. But that isn't because they are more athletic or more talented, it's mainly because of the advancements in training, supplements, nutrition and medicine.
And although it doesn't really apply to basketball, unless you want to talk about the sneakers, balls, and rims, the equipment is significantly better. Bats are made of better wood, baseballs are much tighter, and mitts are top-notch. Golf clubs are light years ahead of what players just 30+ years ago used, and so are the golf balls. Tennis rackets, hockey sticks, football helmets/pads, etc. are all to the advantage of today's athlete.
There's no real reason to think athletes today are superior to their predecessors. Talent is talent. The only grey area is rule changes.