You know what's desperately needed? Player tendencies. 2K is brilliant for introducing this and it makes players' playstyles extremely authentic. There should be tendencies for things such as the likelihood of attacking the neutral zone, the likelihood to set up passes rather than taking shots (as well as key areas where players like to set up, such as Ovi's office for the one-timer). The likelihood to try and dangle around defenders rather than dumping the puck, tendencies towards going to the slot as opposed to skating around the boards.
For example, maybe a player will be more likely to attack the middle if they notice they're up against a bottom 6 dman who is worse at poke checking and positioning than a top 2 dman. Players should be able to size up their opponents and change their strategies based on what they can and can't get away with.
There need to be way more statistics as well (backhand shots, lateral pivots, anticipation, vision, lower body strength, etc). If you implement all these factors, player chemistry can be built around players' skill sets rather than the same old ineffective plays the AI tries to force. For example, when Ovi and Backstrom play together, there's a focus on working the puck in the offensive zone until Ovi is free for a one-timer. A lot of players have skill sets and strategies meant to complement one another. But this never happens bc ai players skate backwards and receive passes on their backhands bc there's no offensive strategy or positioning.
Players need to have individual stats geared towards individual intelligence and the ability to predict plays.
McDavid in real-life games can find key scoring areas because he knows how things will play out 2-3 steps ahead. Because of that, he will position himself in certain areas, pivot to buy enough time for other players to get open, and pass the puck back and forth with the point man until he finds a good feed for a one-timer or a rebound goal in front of the net. Crosby grinds in the lower areas and is extremely tenacious and able to bounce off checks and draw defenders towards him so he can set up other teammates. Meanwhile, AI players just run around like chickens with their heads cut off. There's no patience, no actual coaching strategies towards neutral zone breakouts, and offensive zone cycling tendencies. Players just rush toward the center and don't care if they get bulldozed by a dman for the 7th time that game.
There are so many intricate parts of the game that aren't emphasized bc EA pays such little attention to detail.