So, regardless of whether one uses the Service's updated assumption or the Commission's rates and assumptions, there has been an unexplained swing of $1.
The upswing is not of $1, but of $2. 
mnli hypothesis: The upswing is not of $1, but of $2.  premise: So, regardless of whether one uses the Service's updated assumption or the Commission's rates and assumptions, there has been an unexplained swing of $1.