2. He Had Very Little Support from the Imperial Navy
Yamamoto had found himself quite unpopular with his superiors from the beginning of his term, not only for his opposition to a US-China showdown, but doubly so with the Imperial Army, whose more radical decisions came straight from the Japanese government. His defeat at Midway only fueled the fire, and Yamamoto had lost face with the Army and other senior ministers.
Therefore, Yamamoto was forced to coordinate with Japanese army operations from then on. But the Army often didn’t do their fair share, so many naval actions proved ineffective, only ending in more devastation to the Japanese fleet and their number of men.