Calculating the damage it takes to kill a mob would be easy enough, but calculating the actual AC of a mob is a lot tougher. There are a lot of unknown variables that go into it. It's been a while since I read up on it, but I did some reading and poking at it back when I was thinking about helping out with the emu scene.
AC isn't a single number that can be easily calculated. You could calculate an approximate mob toughness by parsing damage against a mob with 0 AC of the same race and class and comparing average damage per hit and miss rate, but you also have to take into account any innate avoidance or mitigation boosts it might be receiving and things like that. You can't just say mob A has 1500 AC by attacking it for a few minutes without anything else to relate it to.
For example, you may take a test mob that is a human warrior with 0 worn AC and base avoidance / mitigation for a human warrior, and hit it for 100 per hit on average. Then you take mob A that is a human warrior as well and you are only hitting it for 50. There is really no way to relate that 50 damage difference to an actual AC number that has any meaning beyond how it is coded on the EMU side. The EMU server could be coded to say 1000 AC is a 50% damage reduction, and while that would work, it would not be accurate across the board. This would have to be something that is tweaked and customized for every single mob in the game if done that way. Not to mention coming up with the statistics for every single race / class type in the game. Oh.. and let's not forget this code has to work for players mostly too unless you want to maintain a different set of code there. This is a problem P1999 still has afaik, the player AC formula just isn't right. It's why when I played on there a year ago monks were far superior raid tanks than warriors because the AC formula is wrong. And I'm talking even more so than pre live monk nerf.
The you have the further complication of taking into account buffs and such on mobs. You'd have to completely dispel every single mob you are fighting to get values from it unbuffed. Otherwise you run the risk of over inflating values and making the mob tougher than it should be on the EMU server once it gets buffs from the mobs around it (on top of the buff calculated values that you have).
Don't get me wrong, I don't want to discourage anyone that wants to try and produce some solid numbers that can be relied upon, I just don't think it's possible to do that at this point (at least not in regards to AC). If anything I'd say you' should be recording observable information like the amount of damage it took to kill the mob, the average damage per hit (plus a min max hit value), and the number of times actually hit vs the number of misses. Oh and you'd have to store that all with any information on buffs on the mob at the time, buffs on the player, the players equipment statistics (especially the damage on the weapons), the race / class of the player, and the race / class of the mob. If you have all this information, and a few hundred differently geared players contributing to it, it might be possible for someone to come up with an approximate formula (which is probably where the formulas that are out there already came from). But it still would not be 100% accurate and would depend also on an accurate player damage formula on the EMU server to match.
Oh.. and for mobs damage output... take all the above arguments and put them in the perspective of the player being the target instead of a mob. They all apply the same more or less. Players you have the advantage that you have a few more known numbers to work with (like the players reported HP and AC total), but there are still formulas behind this with unknown values that have to be worked out. Like the players Soft AC cap, the players avoidance, natural mitigation, etc.
