A fascinating thread.
If I may chip in with a few thoughts ( no maths and stats from me, my brain canna do that stuff ).
This is obviously the reason behind the popularisation of "Aces" - take an individual who has beaten the odds ( luck, skill and right-place-right-time ) and say "you too can be like this." It aint even remotely true, but it keeps the cogs happy.
However, this is not to say that their exploits are untrue. We all know that the German air-to-air claims were subject to fairly stringent checks and many aces had several victories disallowed because no one was able to corroborate their AAR.
So despite all the evidence given above as to the relative ineffectiveness of fighter-bombers versus tanks, we have to consider that perhaps someone like Rudel DID in fact achieve what he is credited with. Ok, given the difficulty in verifying ground kills, perhaps he only actually managed half of his credited total - say 260 tanks. That's still a huge number, but he is ahead of the curve ( again to relate to fighter pilots, we know that approx. 10% of all fighter pilots accounted for approx. 80% of all kills - to probably misquote a stat ). So yes, there could be many Stuka pilots out there who just plain couldn't hit a tank, but that doesn't mean there weren't some who could, to pull the average up. ( I don't buy that the German Ju87G trials could have been so flawed that they thought it could kill enemy armour when it couldn't - at worst, they must have been testing against static targets, so that could throw results off. )
But, there are also other factors that could be working in Rudel's favour. A fighter ace like HJ Marseille is reputed to have shot down enemy planes with an average of 7 rounds. Now these planes were manoeuvering at high speeds, so it is not inconceivable that a skilled pilot could hit a vastly slower ground target from a somewhat slowish plane.
Ok, let's consider that our hypothetical Rudel has hit the target tank.
He is firing a so-called "dinky" 37mm. The ammunition is tailored to tank killing, so that helps offset its dinkyness. He is firing from above/behind/to the side which will also help. But most importantly, not all tanks are created equal - the Soviets fielded "obsolete" tanks ( BT7's, T26's, T28's ) right up until the end of the war ( in recce and other roles ) - so did the Germans, fielding PzII's in the recce role. Not to mention the Lend-Lease Stuarts and Shermans. All of these would be easier to kill than a T34/85 or IS tank. Plus, our target "tank" could be an open-topped AFV of some kind. To our pilot, it's just Thing-With-Tracks-and-Pointy-Bit = Tank.
So it is within the realms of possibility that an above-average pilot like Rudel could pull off multiple kills on tanks without skewing the overall average ineffectiveness of the tank-buster aircraft.
Bear in mind also that as described for the West Front, the fact that the aerial attack was ineffective may not preclude the chance that the crew of the tank would panic/bail out/run away/get killed by humble infantryman's bullet. And even if the Stuka only immobilised a T34, say - in a place like Kursk, the crew is unlikely to stick around. This would be a valid "kill" for the pilot having removed a weapons system from the battle ( not really caring whether or not it can be repaired )
It's all very interesting.
