The AI is toothless on Professional - I can't use the sliders to make it a challenge because the difficulty level is the overriding factor in the AI's style of play, as shown by World Class being a different game from Legendary (the same team will move the ball around entirely differently on either difficulty, which shows how little team individuality there is anyway). You can't just put shooting/passing accuracy to 100 and fix that - their decision-making (which there's no slider for) is terrible, and so they gift you possession by running into you etc...
The problem I have isn't in experiencing "difficulty winning some games", it's in trying to press an opponent and A) my player refusing to break into the invisible circle around the opponent, B) the opponent moving in circles around the ball in a daft-looking, entirely unrealistic and endlessly frustrating fashion (it's like playing online against someone who passes to a defender with 90+ strength and then holds onto the "shield" button for 90 minutes - I play against the AI almost entirely to avoid such wankers).
Every pass feels unique, every shot too, and the game is outstanding in many areas. But I can't get past it being frustrating and boring to play, against the AI and against another person online (the button lag, which was non-existent last year, is frustrating as hell too).
Just my opinion, and I can certainly see why someone would fall in love with what the game does well. But for me, AI is the backbone - while every match has the same tempo and patterns, I can't play it. The frustration is that it's been like this for years, and will probably be the same next year. Offline players tend to buy the game no matter what, and there's no card packs for us to buy, so what do they care.