I respectfully disagree. The sliders DO work, at least in my experience. Try this: Go into an offense only practice mode, turn QB accuracy to full, tell your reciever to run a streak (playaction seems to work best - they just keep running), and throw the ball as far as you can - It'll probably go about 70 yards and right on target with any high throwing power QB. Then change that slider to empty, reselect the play (that's important - the slider change won't register until you do), and run the play. Not only will it not go 70 yards (less than 40 on the average), but it'll also probably be far off target - to the point where another reciever will probably have a better shot at it than the intended. The slider is a range slider as much as it is an accuracy one.
You can pick up the effects of other sliders too in the same way - like awareness (watch how corners react to short curls) or WR catching (watch Chad Johnson drop 7 out of 10 passes with it zeroed out)
One last thing.....You probably know this already, but the CPU gets attribute boosts on All-Madden, which I believe causes a lot of the cheating complaints. And if you need proof of that, play a mirror match game (CHI vs. CHI, for example) and check out the vision cone difference between you and the CPU. You'll see for yourself - it's a very noticeable size difference. Compare that with all-pro and you can see which level makes things more equal. Granted, it's about the only difference you can prove exists, but if there is this kind of visual evidence, is it that much of a stretch to think that other parts of the CPU's game are getting boosted as well?
Sorry for the long post. I mess with these sliders all the time (sometimes more than actually playing the game) so I feel like I have to say something when I hear that they don't work.