Assuming you have a MUD that has a reasonable player-base AND a good handful of builders (not at all a given these days), I prefer to balance things via gathered statistics, rather than trying to shackle the builders into a whack-a-mole mindset of automated balance code.
Once you know your goals for the game, you should have a pretty good idea of how fast people should advance, and a good idea of how much content they'll need to consume to get from A to B. If you can log enough data, you can look for outliers that don't fit your expectations, and those are generally the things that will need adjustment.
That's part of the reason I want SQL support in my game. It would be nice to have the game data pulled from there, but it is far more useful to log statistics about every kill, every quest reward, every death, everything you can without slowing the game's performance to a crawl. Even if you just dump all that to a file and then have a script push it to a database, it's gold for the mining.
The good old AD&D rules used to say that typical mobs had (level * d8) hit points as a guideline. So, a simple query to check the average hit points of mobs when they are created should find all the level 50 dragons who have 10 hit points, and the level 1 death-squirrels that have 999 hit points. Anything that's an outlier will show up, and you can then refine your query further, or go look at the individual results. If the mob has too few hit points, but also loads with plate mail, or is a caster with nasty spells, or has less than normal rewards (garbage drops, no cash)... all is well.
You may not be using D&D rules, but you better have SOME well-defined system, or you're already in trouble before you get started. If you change your system down the road, remember you really now NEED to go back and adjust all your content.
If you're on your own, this is a LOT of work, and so wanting to automate it by code is very appealing. I still think it's a mistake, but that comes down to my not liking to be told that I can't do something because it doesn't fit the pattern. You can have a hot dog with ketchup, mustard, both, or chili. You can't have mustard AND chili, because it's not on the menu. Bah!