You're wrong. Kakashi did NOTHING when naruto is in BM. Pay attention, I'm talking about BM.
The only info naruto had is how to stop them. He still had to locate the rods, and take them, and it was very hard to it. All of that, he did it in his first time BM within 5 minutes.
The only thing hachibi did was stopping a bijuu. He only helped BM naruto once, and naruto could've withstood the atack.
And another thing, naruto was pushing them back, he even managed to hold all 5 of them on the ground, and managed to do a bijuu dama to match theirs combined.
Yeah, he can keep up with 5 bijuus.