Right, I was responding specifically to this point, which you mention above:
So, the first point I would make is that, if you want to rank the greatest ever in some sport, I don't think it's reasonable to say that player A cannot be the greatest ever if they lose to (or have a losing record against) player B. That's the original point I made.
If you want to think in terms of skill level, my second point would be that I don't think overall skill level equates to, or can be measured only with respect to, wins and losses against one specific opponent. Again, to use Nadal and Federer as the example, I think it is possible for Federer to have a losing record against Nadal (even 15-24 as it now stands), but to be an overall more skilled tennis player, as would be evidenced by his overall accomplishments as compared to Nadal's.
Since greatness or how good a player is overall in competitions like tennis and pool are not measured so easily and objectively as how fast one can consistently run a mile, the comparisons and rankings are more difficult and more complicated to make (though I still think reasonable comparisons can be drawn in most cases).
I didn't follow this conversation but I agree with the bold statement. That's why I didn't put Efren over SVB. SVB's overall skill is better than Efren's but if they were both at their peak, I'm not sure who would win.
I put Archer, besides anyone else, because as mentioned, he influenced my game and was a top player then and changed the way a lot of people viewed pool.