I think we should be able to, but I don't enjoy math when large, negative numbers are involved
Too true. In both the save and the pass, the player takes himself out of the play entirely. That has to balance out the advantage to some degree. In fact, the nature of that pass is such that it's likely to leave the passer farther from the play than the save (which often is either a relatively short pass, or a lob to give somebody time to get under it and the player to get back inbounds).
By going around the screen, the offender may well put himself in a position for an easy, open score. That would be using one illegal advantage to create a further advantage.