Why is Katsuyori a weak leader in samurais tale?

Apart from the big mistake he made at Nagashino, Katsuyori was a overall good commander. He just got the job into his hands to fast, as he showed that when he did not have the whole responsibility he did great, such as Futamata and Mikata ga Hara. Even when he was in charge he won at Takatenjin. If Shin.gen had died a slow death, from old age maybe or at least a slower and more excepted death. Not as fast as he did, and perhaps on his way to Kyoto. He might have the feeling he might that

“I can do this on my own."

" What honor is there for me if I use my fathers strategies and his generals?

"I want and can do this myself, my way!”