We have only the Halder's vision of the events.
VB wrote a diary too, but because Halder wrote it day after day, it is the more accurate source we could have.
This is how Halder describes the events : Hoth was ordered by VB to strike Voronej. But Hoth feared the concentration of troops in the city. That's why he asked for support from Weichs. That was the failure of VB.
Surely VB wanted to stuck to the initial plan (strike Voronej), he didnt listen to Hitler who didnt want anymore to strike it. VB smuggled, he counterfeited reports in order to get Hitler' support.
But what are the consequences of disobeying?
The consequence is clear : VB is responsible of the useless losses in Voronej, is responsible of the delay in encircling soviet armies in the south. VB is somewhere responsible of the failure of Fall Blau.
The problem is that Hitler could not trust his generals and his marshalls. They were reluctant to execute Hitler's plan. How do you want Fall Blau to be welle executed since Hitler had a resistance inside his own HQ ?About Stalingrad in July 1942, Hitler forgot. All sources criticize him precisely for weakening the Stalingrad direction. At any cost, Hitler sought to take Rostov, despite the protests, for example, Halder.
After VB's disobedience Hitler had to check personnally everything on the front... it was a huge task... he could not sleep enough... he could not focus anymore on the strategy as a Leader should have done...
And there it is, you have the big failure of Fall Blau.