The only part this simulation that does'nt always ring true to me is the fate of leaders of badly lost battles.
At the moment a leader can just be killed in battle or end up "recovering from injuries" for a 2-4ish turns in a nearby city after his formation is destroyed. Both realistic outcomes but the "recovering from injuries" fate always happens - surly a leader could escape the destruction of his formation uninjured too.
Also a leader's "recovering from injuries" period could be a lot longer than just a few weeks depending on how badly he was wounded.
The "recovering from injuries" fate also happens when a leader looses a seige - in this situation would it not be more realistic for him to be captured as being in a siege he's surrounded & trapped. The possiblity of capture would also exist if a leaders force is beaten in open battle by an overwhelming enemy (esp with a lot of cavalry!)