I recently went looking for slider downloads and found one complete with Rosters, settings and sliders. I used the Pro Sliders settings included and though the realism increased (e.g CPU team doesn't score at will everytime during 2nd half, when theiy're down or crunch time), it became rather easy. So i bumped up the difficulty from Pro to All-star and games got more challenging and closer games. I'll try bumping the difficulty level higher and see if I really get a challenge.
One other thing, it is easy to find Superstar Slider Settings and HOF sliders as well, so i'll probably look into those too instead of using Pro sliders with higher difficulty settings.