If you are looking for universality in evaluating this draft then it is impossible to achieve, as simple as that. Just above Skizzo quoted a source saying had O'Reilly and Grimmett played as many tests as Warne they would have taken 700-800 wickets, but that is not how it works. Yet, any cricket historian worth his salt would tell you there's literally nothing between Warne and O'Reilly when it comes to their cricketing legacy, but Warne did take all those wickets playing during all those years and keeping up that standard, so there IS something between them. Graeme Pollock, again regarded as one of the finest batsmen to grace the game, played 23 games and averaged 60. Sachin Tendulkar played 200 games and averaged over 50. Can we find players who for a similar span - say 23 games - averaged that much and dominated opponents similarly? Possibly, quite a few. Most of them had to continue playing and as a result their stats came down, naturally. No one can absolutely comment on what would have happened had the likes of Richards, Pollock, etc not been restricted from Test Cricket, hence the Big Dunc analogy.
For me really comes down to the individual player and the circumstances due to which he wasn't allowed to play as long as others. In football drafts we usually take the 3 year peaks to evaluate, but that's not the case here and the different formats make it more complicated, so I personally apart from obviously the test stats, would be taking a lot of other stuff, like their influence on the game during and after their career, what their peers had to say about them, etc. Like I quoted above, Tony Greig, one of the more educated personalities in this sport describing Richards as the finest batsman in the world, at a time where there were a few others, including Viv Richards. Or Richie Benaud who described S F Barnes as the greatest bowler to ever play the game, and he knew everyone from Lohmann to Glenn McGrath, based on nothing but literature. These are not fan based opinions, but coming from some of the most sincere students of the sport, like Benaud. So you have to give some weightage to that.