Lee in the Union

The author does not state Sherman was the first killed, and he has Grant die later in the battle as the Confederate attack develops. Ultimately, however, neither of these detract from the basis of the Confederate victory; a better deployment and a movement that involves not running to the Union Gunboats at Pittsburg Landing. Comparing this to Pickett's Charge ignores the very, very different tactical basis of both engagements. At Pickett's Charge, the Federal defenders were awaiting the attack, which had to come across an open field at them. At Shiloh, however, the Federals were caught completely by surprise and Grant compounded this failure by having ordered his men not to construct entrenchments. In short:

Shiloh: Unprepared Federals caught by surprise with no fortifications
Pickett's Charge: Fortified Federals expecting an attack in the open against them

Further again, you need to consider that comparisons to other battles ignore the changed landscape and orientation of the battlefield. At Fredericksburg, the Confederates were entrenched and allowing the Federals to attack them but, further, the Federals had an open line of retreat. Same goes for Antietam. What the author wrote was Johnston's plan, which was a good one; instead of focusing on Pittsburg Landing, the attack maneuvers the Union forces into such a position that they have no escape due to the prevailing swamps and creeks of the area. If to his rear is flood, impassable swamps and to his front is the Confederate Army, what else can be expected but the total destruction of the force? See what happened to Harper's Ferry in September of 1862, where Jackson destroyed an entire force of 12,000 Federals.

Finally, "No Plan survives Contact with the enemy" isn't meant to be a truism, but to instill a sense of improvisation as the particulars of the battlefield shape up. The vast majority of military operations do proceed as planned; otherwise, how does anybody win wars?