What you saying is that there has been a 41% increase in X over Y. However, this increase does not represent the absolute difference between X and Y because it is only a relative increase.
The only way to express the true difference in absolute terms is to set X as the 'Standard' and call it 1. We can now arrive at a 'true' ratio and therefore make a direct comparison between X and Y.
Therefore, if X = 1 and Y = 0.71 (a ratio of 1 : 0.7) then the absolute difference is 0.29 (or 29%). In approximate, but absolute terms, X is a 'third better' than Y.
(And in the case of Bradman and Sobers, it makes 'intuitive sense' to call Bradman a 'third better' than Sobers as this is about what I would expect with respect to the talents and effectiveness of the two batsman)