I think having Albert Sidney Johnston survive Shiloh might have given a commander good enough in the West for the either the Army of Tennessee or the Army of Mississippi perhaps just as good as Robert E. Lee in the East to at least get the likes of Braxton Bragg, P.G.T. Beauregard, William J. Hard, Leonidas Polk etc. coordinated now ASJ wasn't all perfect but he did bring a lot of experience to the table for the Confederate Army given his decades worth of service in the Texan and United States Armies in the Texas Revolution and Mexican-American War.
I wonder about that sometimes. I find A. S. Johnston is hard to actually form a hard and fast opinion about. He might have turned out to be very good, but there really isn't enough of a record to determine if he was.
He did a good job on some things and a bad job on others.
- Polk and Beauregard messed up the Kentucky situation for him by invading without authorization when the he needed time more than anything else. That led to losing Paducah and the mouth of the Tennessee River, which led to losing Henry & Donelson and Nashville and the upper Mississippi.
- Henry & Donelson is probably an indication of a bad choice by Johnston, but he had to make one among ugly choices He was too weak to hold what he needed across a wide front. In hindsight, he should have gone in person to Henry & Donelson to straighten that position out. Buckner might have been OK, but Pillow and Floyd surely were not. Johnston making a visit or taking command might have prevented disaster or made it less bad.
- Faced with the collapse of his defense after Donelson fell, Johnston had the sense to concentrate and strike back.
- At Shiloh, Johnston does start to look a lot like Bobby Lee. The sense of strong character and battlefield presence is clear. His death chops it all off before we can see what Johnston would have become if he had lived.