Mob Spawns are never tidy as far as maturities go - even on LA's with locked maturities. There will always be a some outliers from average. I have always considered the distinctions like this:
Low Maturity spawns are those consisting of the bottom 4 ranks - Young to Provider (or equivalent) with only an occasional exception. (if the maturity level is set to minimum, there will still be a fair number of Mature's and a few Old's)
Medium Maturity spawns are those made up primarily the Guardian to Alpha (or equivalent) with some exceptions on both ends of the range.
High Maturity spawns are those consisting of the top 4 ranks - Alpha to Stalker (or equivalent) with only an occasional exception. (if the maturity level is set to maximum, there will still be a fair number of Old Alpha's and a few Alpha's)
Having said that, it is only a general guide. I assume the settings are on a slider as spawns vary. Also some spawns of different levels overlap to create more complex spawns.
Peace, Miles
