i am not a master of rules but i believe it works something like this.
as you raise the dead player he becomes a zombie and will take on the zombie attributes and lose those of his previous position. as he does he will cross over from the oposing side to yours therefore the oposition team will lose his worth in Team Rating and you will gain the zombies worth.
in effect you will not pay for him from your tresury but you will gain the team rating so you will have to put the cost on the roster
hope that comes over clear