I think that when people are sceptical of Bradman they are not really questioning his batting skill, footwork, or reflexes. But rather they are calling into question his ability to maintain motivation and concentration during a gruelling and concentrated schedule of cricket formats.
In other words, it would be very interesting to watch Bradman as a member of Bill Lawry's Australian side that toured India in 1969/70, then South Africa straight after. It seems quite reasonable to surpose that Bradman would have come unstuck like the rest of the top-order when fronting up to a rampaging Procter on a Cape Town green-top after battling for a couple of months on the dusty pitches of India. Fatigue and contrasting conditions may have got the better of him.