High yielders aren't always the "best" colony.
When rearing queens we are often told in books and by speakers to breed queens from our "best" colony, but what is our best colony? If you asked the majority of beekeepers they will probably tell you it's the one that gives the most honey - and so will the writers and speakers. It is always assumed the yield is related to genetics, but I think this is yet another example of beekeeping's "false logic". We are not in the same situation as cattle breeders, where they can measure the quantity of milk a cow gives against the amount of food it has received, they also have full control over the parents on both sides.
With bees there may be a small genetic element in the amount of crop they produce, and I wouldn't argue with that, but there are other reasons why a colony will produce the crop it does, these include:-
There are probably several other reasons as well, but these are the ones I can think of at the moment. What I do know is that bees aren't lazy - well not unless they are those very soft light yellow things that sit about if the sun doesn't shine enough for them!
I hope I have given you enough information to persuade you that high productivity may not always be genetic, therefore your highest yielders may not pass that trait onto their offspring.