It's funny either way. You loose yardage from your passing stats even though you didn't throw a pass on the play. Like, you could complete one pass for 10 yards, then get sacked a bunch and have a stat line of negative yards even though your only attempted pass was completed for 10 yards.
Maybe just not subtract sack yardage from anything, just count it as it's own stat? Interception returns don't get subtracted from passing yardage, and that seems a more viable thing than subtracting sack yardage.