
I would hope both, to preserve the best traits and improve in that more of the dogs should exhibit these desired traits, in other words that the quality in the breed as a whole should be equally high, not just the odd outstanding example.
In my breed the best of the dogs of 50 years ago would still be able to win in the ring today, though perhaps there are fewer outstanding animals today, but maybe fewer really poor quality ones too. A lot depends on how big the population is, as we are much fewer in numbers than some decades ago..