The most meaningful stat is games won. I know that no one can win all by himself, but there are certain players who make everybody around them better AND they have their focus on winning the game.
Much of game dynamic does not appear in the stats.
When a player takes control of the game, as he dictates the game that includes what happens and what doesn't happen. On defense, for example, some guys put up shot blocking numbers, other guys somehow disrupt an offensive player's style of play to the point that they become a non-factor. Again, no stat reveals that.
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There is A LOT that even our most advanced metrics are NOT 'picking up' and measuring properly. This is true.
What stat shows how utterly lost LeBron James appeared to be in the 4th Quarter during the Finals last year? There isn't one, won't ever be one---but we all know we need one if we're going to judge everthing on advanced metrics. Larry Bird LOVES LBJ... thinks he's the best player in the NBA & believes he could someday be the best to EVER play----but Bird candidly said he 'doesn't know what his deal was' in the Finals' 4th Quarters last year (when asked in an interview with Magic about the Broadway play about them).
If you're going to be the GOAT, you can't be indecisive, ineffective and passive with the Championship on the line.
Another thing regarding the 'greatest ever' potential for any of the current players: everyone has to come to grips with the fact that, despite all of the pontificating regarding the athletic supremacy of the players today---that the NBA has dumbed-down the rules for ball handling, making it markedly easier to dribble drive, get to the rim and set yourself for a shot.
I honestly have no idea what LeBron James would do if he could not take gallop-steps (and typically 3 of them) through followed by a stop and hop step as he maneuvered through the lane BEFORE shooting the ball.
You used to have to catch a ball and keep a pivot foot locked to the floor without dragging it or begin your dribble before moving both feet. Now you can catch a ball and HOP... then start you dribble and take your shot.
I remember back in the 90s, they moved the 3pt line in to HELP players shoot 3s. What happened was suddenly EVERYONE thought they were 3pt shooters-----and the league became a zoo of clearouts and 3pt FGAs... and the art of the mid range jumper became lost. MJ became a pretty good 3pt shooter, but Stern realized it was ruining the league overall----so the line was moved back after (I think) 2 years (maybe 1?).
They have tried a lot of things since the 80s to artificially enhance offensive play.
Kinda funny how the athletes are superior---but the rules governing ball handling now have to be restructured to help them. It really clouds how good these players are relative to ones in other Eras.