There are several reasons for a split stat. If you have any injuries they effect the model injured giving a split stat, EG: Broken leg gives -1 move which would be shown on your wizard as
Move 6/5 this modifier does not trickle down to your apprentice so he would still have a 6 move.
This is also common when a wizard is wielding a hand weapon and a dagger giving him a +1 fight shown as (for a base wizard) Fight +2/+3 and again this doesn't trickle down to the apprentice.