Right Derek, I thought of that. That leads us along the unihistorical path though, something that Paradox, from my impression, hopes to avoid.
It's possible to cure this problem by bringing in generic leaders with combat values completely hidden. These values would be unknown to the player, but randomized around the basic country values. After a battle, win or lose, there is a small chance that one of the leader's values is revealed. In this way, while you can't raise a Napoleon a la Heroes of Might and Magic (unhistorical), you can "spot" one by making various generic leaders fight several battles. Trouble is, the historical Napoleon would still have to go under this setup - but this could be an option at the start of the game. "Fog of Generalship" on, anyone?