Going back to the initial example, it is not just two floating modifiers. It is two floating modifiers (MAP and sweeping) before any of the bonuses and penalties from the combat are calculated.
At low levels, there was generally at least one additional modifier on most attacks. The most common were flat-footed, cover, and bless.
Just for clarity: Neither cover or flat-footed modify attacks, they change the targets AC and are usually calculated by the attacked and not the attacker.