I'll tell you one thing I toyed with for a long time and agonized over...
The theory would be that you use the scores of each (in-game) player as a guideline. So, Ricky Ponting comes out: his average score is, say, around 50. Therefore the timing window is very forgiving to the player up to 20 (assuming they are attempting the right sort of shots of course). The timing window then becomes more challenging up to 50. Between 50 and 100 it becomes harder, and then above 100 you are basically on "hard" difficulty.
Eventually it becomes incredibly hard beyond 200 and if you get anywhere near 300 you're then on a timing knife-edge.
Obviously for every different player, the same rules would apply but using a lower/higher average. It wasn't a hard average either: it used the person's lowest and highest scores also as outliers to make it a bit more accurate.
Experiments were very successful in that they produced the desired sort of scores, but ethically people found it hard to swallow and felt that it was "cheating". My answer was that ALL video games have SOME smoke and mirror elements, but I was comprehensively outvoted. People just felt it was wrong.
Personally I felt it was a good leveller: to achieve a batsman's best you would have to be very good at the game, but a beginner could at least score something vaguely in keeping with the abilities of the players he was playing with (essentially, they were kept afloat by the abilities of the in-game players!)