I think sliders are fine for people to adjust so they can get a competitive game for themselves, but I'm not one to mess with them myself. I think a lot of people fall into the trap of endless slider tweaking, in search of that ever elusive "perfect" set of sliders that gets them a realistic game. Yet, things happen in sports all the time that seem out of the norm. I remember a Red Sox game a couple of years ago with 4 back-to-back HRs. If that happened in the videogame, someone would go in and change their HR sliders because it's not "realistic."
I think it would be easier to just have an "arcade" difficulty setting, for people that want the game to be more arcadey and a "sim" difficulty setting, in which the devs set it to what they feel is the most accurate to the sport they could make at the time. Sliders could still be in there to teak difficulty, if you wanted.