First, I didn't rely on Foote and Burns only. Catch up with all the posts concerning casualties. See #59 above. The consensus has twice as many casualties as Rhea. When it comes to NPS, civilwar.org, Catton, Foote, McPherson, Trudeau and Eicher vs. Rhea, I'll take the first seven sources.
Those were the two you specifically mentioned in the post to which I replied--two people who are not historians and really not scholars of the war.
The consensus among scholars today goes with Rhea. You won't find many current scholars who substantially disagree with Rhea's numbers.