Studies have been done with Grandmaster chess players, where they've been shown chess pieces on a board either midgame or near endgame. The masters could backtrack the play, and state what moves led to that positioning, and could see where the game was going to end. Sometimes, they were shown pieces on the board that were just placed randomly, and the masters could not recognize what moves led to those positions. For all the billions of possibilities to get 40 moves into a chess game, the Grandmasters need only memorize the percentages of probability for moves that could lead to victory or failure, and all else was meaningless. Early in his pro career, Gretzky was tested in a similar way, and when shown stills of game situations, could accurately predict what was going on the ice five seconds before the photo was taken, and what did happen five seconds afterwards.
In chess, there are 400 different positions after each player makes one move apiece, 72,084 positions after two moves apiece, over 9 million positions after three moves apiece and 288+ billion different possible positions after four moves apiece. When Kasparov first played against Deep Blue (an IBM supercomputer) in 1996, he won 4-2. The computer programmers were stunned when they realized that Kasparov was playing and understanding the game up to 20 moves in advance of the play. With this in mind, they went back to reprogramming their computer for a year after the tournament, and played Kasparov again in 1997 with Deeper Blue, a revised computer which ultimately beat him.
In hockey, the positional possibilities alone surpasses the moves in chess. Five players aside plus those on the bench plus who's tired, who's sick or healthy, varying skill levels, etc. mean the possibilities of what, when and how are infinite. However, the probabilities eliminates most of the possibilities as to what might happen on the ice. I might skate hard and shoot on a breakaway, but I won't attack the net skating backwards with one hand on my stick and holding an ice cream in the other. Kasparov doesn't have to memorize every possible move in chess, just the ones most likely to happen. Him knowing what's likely to happen 20 moves into the future gave him a certain advantage when playing. Gretzky, likewise, having a five second advanced notice as to what will probably happen on the ice gave him a tremendous advantage. A good NHL skater can move about 3/4 the length of the ice in five seconds. That's a tremendous head start over other players that didn't see the game unfold as he did. Goes a long way to explaining the 200+ point seasons in spite of the fact he was not physically overpowering, overly fast nor possessing a tremendous shot.