FM2012 difficulty.

[Keyzer Soze]

The AI cant look at players like you do and tailor it's instructions to them. It sees players as an Age a position a reputation and a CA.If you imagine in their prime Beckham and Giggs having the same CA and being RM LM respectively the AI would assign them both the same instruction while you could examine their attributes and set different instructions to get the best from both of them.
Lots of problems with AI squad building can in my opinion only be addressed by rewriting the AI to look at players in a much more detailed and human manor.

I dont think that the AI its so limited, but i agree that we have tools to take the best from the players.
I dont think that the AI would give Giggs and Beckham the same instruction, but i'm sure that it will give them standard instructions from the TC (winger with attack duty to giggs, and perhaps wide midfielder with support duty to Beckham).
We, human managers, work from those standard instruction but tweak them according the player attributes.
This could be the main reason why players play better for human teams. Despite, i still believe that we must not generalize because like i said in my post about Nicolas Gaitan, there could be logical reasons why the player plays worst in the AI team.

Perhaps this could be the next step for the AI: starting from the standard TC instructions, have the ability to tweak them to take the best from the players. (this is valid for the team and player instructions)