The contra argument is that with Reichenau as a mentor at Army Group South, Paulus would have had firmer direction from above which was lacking in Operation Blau. And that’s what you’re supposed to have a Army Group C in C for.
Glantz paints a different picture of Paulus as army commander anyway. But we can discuss that next year.
Paulus was a product of the General Staff, the ultimate “Old Boys school”. If anyone was a mentor, it was Halder. I have no problem with Paulus being the Chief of Staff of Sixth Army. It’s what he did.
BUT, Reichenau shouldn’t have recommended him as a successor,Berlin should have opposed it, and Pauklus should never have commanded the largest single combat formation in the German Order of Battle.
And insofar as firmer direction from Reichenau [if he had lived], a couple of notes. First, Blau involved two distinct thrusts by AG South, and the primary one was the Caucasus. Paulus had what was initially, a subsidiary role as envisaged by the plan. Covering Kleist’s flank. So the amount of time Reichenau had to oversee Paulus is problematic. Second, as evidenced by subsequent events, Hitler was almost de facto commander of AG South himself, and we know how that turned out.
What Reichenau’s death did was remove one of the few military voices Hitler would listen to [like Model would be, later]. He just might have kept Hitler on plan, with the result that Paulkus would have been doing what he was charged with, and what he was potentially capable of, guarding a flank defensively.