Gettysburg Day 3: What Think You of This?

I don't pretend to be a Gettysburg expert, but I've read some about it. I have never, however, heard the following. Can any of you who have studied the battle comment on the following:

Is there anything new and important to say about Gettysburg? Perhaps so. Perhaps Lee's imagination and patience did not falter after the abortive attacks on the second day. Perhaps his plan for the third day was the most brilliant of all: he just kept the fact of its failure secret out of concern for his army's morale. That plausible plan concerns something everyone knows -- J.E.B. Stuart's belated return on July 2 -- and something many people may not know" the action Stuart's men fought on July 3 well behind Culp's Hill. It is always assumed that Stuart just meant to disrupt the federal troops' supplies and reinforcements or harry their expected retreat. But strong circumstantial evidence suggests that Lee sent Stuart around the northeastern tip of the Union lines with orders to circle back west and charge Seminary Ridge from the rear in support of Pickett's charge from the front. Why didn't Stuart deliver that mortal blow? Because 2,700 cavalrymen from Michigan, in fighting trim thanks to Hooker's attention, defeated Stuart's gray ghosts about four miles short of their goal. The Union general who rallied his men with the cry "Come on, you Wolverines!" was George Armstrong Custer.

The accompany footnote states, in relevant part, "On Lee's secret plan for the third day, see Tom Carhart, Lost Triumph: Lee's Real Plan at Gettysburg and Why It Pailed (New York: Putnam, 2005)."

Walter A. McDougall, Throes of Democracy: The American Civil War Eara 1829-1877 (New York: HarperCollins 2008) (emphasis added).

Have you heard of this? Is it credible? Do you believe it?