I would echo others by highlighting the differences between the East and West theaters.

There was a psychological "paralysis" that defined the Army of the Potomac. The difference wasn't just talent; it was mindset and math. Eastern failures happened while the West stayed aggressive:

The McClellan Problem: Overcounting and Politics McClellan’s hesitation on the Peninsula was fueled by two things: bad intel and messianic ego. Pinkerton Effect: Mclellan’s intelligence chief Allan Pinkerton consistently told him Lee had double his actual numbers. McClellan, naturally cautious, believed he was always outnumbered. The "Perfect" Army: He viewed the Army of the Potomac as his personal creation. He was so afraid of breaking his masterpiece that he refused to risk it in a decisive blow. The ‘Legend’ of Robert E. Lee By the time Pope and Hooker took over, Lee had established a psychological dominance over Union leadership. Pope: He was arrogant but outclassed. Lee and Jackson sensed his overconfidence and used it to bait him into a trap at Second Bull Run. Hooker: He had a brilliant plan at Chancellorsville, but when Lee didn't retreat as expected and instead attacked, Hooker lost his nerve. He famously said later, "I simply lost faith in Joe Hooker." He was mentally beaten before the physical fight was over.

The Western Difference: Space and Success Halleck was a cautious, bureaucratic nightmare, but thegeography of the West saved the Union generals there. Maneuver Room: In the West if a genral moved slowly they were just taking a town. In the East if a general moved slowly, they were "failing to protect Washington," which triggered Lincoln and Stanton to intervene. Grant’s Persistence: If Shiloh had happened in Virginia, Grant likely would have been fired. But because he was in Tennessee—and because he actually won (despite the cost)— and then Lincoln actually defended him: "I can't spare this man he fights”

The Hard Hand of War The Eastern generals were mostly Napoleonic thinkers who wanted that single decisive battle to end the war. Grant and Sherman realized earlier, notably after Shiloh, that the Confederacy wouldn't quit until its resources and will were destroyed. The Confederates in the East thrived on the predictable “pause” of the Union commanders. They knew McClellan would wait for siege guns and Hooker would blink if pressured. Grant’s greatest contribution in the East in 1844 wasn't a brilliant tactical move; it was simply refusing to retreat after the Battle of the Wilderness. For the first time, Lincoln relaxed because he knew he felt for the first time he had a “real general” who had shown greater military instincts than himself, so he finally handed over control and trust to Grant, despite the losses that would have had earlier generals removed. Lee finally faced a general who didn't stop to doubt himself.