Sevensan, how often did you use skeleton summoners in the game? How often did you free Izru and Vidomina from prison? How often did you ultimately win by using Izru and Vidomina? Here, it is important to be specific in order to correlate the win rate of these necromancers with that of logisticians like Tazar and Craig.
Or, perhaps it would be fairer to stipulate that specialists – logisticians, armorers, and offensive units – should upgrade their special skill to the expert level last. And even then, their names will probably still appear frequently in the reports!
And as another option regarding these necromancers: allow them to practice necromancy as experts, for example, starting from the 3rd week (or on a specific day).