Let's say that my action is to throw a curtain over a cultist so he can't see when I stab him in the kidney. In 4E I make an attack roll, probably Dex vs. Ref (Ref because I'm the DM and I decide that he tries to duck out of the way).
Right there I know the math more-or-less lines up; the PC has a decent chance of scoring a hit, but it's not a given; the better the monster is, the worse the chance of success, and quicker monsters have a better chance of avoiding the attack than a big brute.
In earlier versions: Save vs. Petrification? To hit vs. AC? What AC? Any proficiency/non-proficiency bonuses or penalties? AoO, if that misses, melee touch attack using Dex instead of Str, then a Reflex save? Just a Reflex save? What's the DC? Or no Reflex save at all?
If I pick any one of these, how will the math work out? I'm not sure. It doesn't scale by level as well.