Playing on the hardest difficulty as Parramatta (20min games), just finished my 3rd season. I won the grand final 46-12 against Souths despite being down 12-0 halfway through the first half. Won the final 58-6 against the Cowboys. I'm pretty much demolishing everyone now, winning by an average of about 25-30. In my first season I won one game all year. The next season I won the grand final easily.
A couple of things:
3 seasons in and the cpu has never missed a conversion.
Intercepts are completely faked about 80% of the time. What I mean by that is that the cpu defender is not even in position to take the intercept. He's just somewhere in the general vicinity of the ball and he just ends up with it. Often he'll take the intercept while he's on the other side of the receiver. I once had the marker intercept one of my passes.
The cpu is terrible on attack. They basically only ever score off intercepts or knock-ons (and bombs). They throw an enormous amount of forward passes. They get caught for a lot of them, though they get away with a lot too.
Passing to the player next to you is a problem. A lot of the intercepts I throw are from trying to pass to a player next to me who is running into a gap, but the pass cuts him out even though I don't press the cut out buttons.
Players still (after all these years), run for balls near the sideline and just run out or even worse, the ball is already over the sideline/dead-ball line and they touch it before it hits the ground.
Players overrun the play way too often. Sometimes I'll go through entire sets where it's hard to pass to a teammate because they're all 5-10 metres in front of me.
Bombs. I diffuse them quite often, but I also let in tries from them. I get in position, press the correct button and... sometimes the player just does nothing, sometimes he'll jump and contest the ball, other times he'll jump at the same time as the opponent, but the opponent will have taken the ball, planted it down for a try and stood upright again before my player has even come back down to the ground, like it was a slow motion jump. The replays show this up particularly badly.
Oh yes, the replays. My god, I can't believe a game that's not more than 15 years old doesn't have proper replays. Score a great try, but only get to see the player run across the try-line.
And then there's the cpu player's slow motion dives for tries. You'll have your defenders in positon and then the cpu decides it's slow motion try time and they'll just (very slowly) over the line straight through your defenders who aren't allowed to do anything about it.
I could go on. I know it's probably all been said before... but not by me.