Isn't this a bit of an obvious question/answer? Handpicking is just an extra layer of quality control - not an ultimate barometer of a bats performance, though nonetheless it weighs the chances of a better bat (and more importantly removes the 'plank' risk) in your favour.
You could stretch it to say the person hand picking indicates a less of a 'blind-churny-mail-order-y impersonal retailer that could be selling bats with the same consideration to that given to their tennis racquets'.
And stretch it even further to indicate that the people not picking are (therefore) at a disadvantage because they get sent what's not picked or get targeted by the retailers as not as choosy as HandPicked Ltd, and ergo a good destination for the lesser models in a given grade.
You have a guy picking bats versus the guy not picking. Surely it's inarguable, in that specific paradigm that the handpicked person will have the advantage of selecting better bats?
The question is how material is that factor.
And how likely is it that the BlindChurnMailOrder guy has a better relationship with the manufacturer (owing to scales and 'ease' of business) and who's the more lucrative channel and as such gets sent the better stuff to keep the relationship 'sweet'?
Have said it before though, and am in total agreement with Buzz - a good performing bat is accurately detectable, (in a rawish un-knocked in state) by many fewer people than we appreciate.
However I disagree slightly that a bat has a great 'feel' (lets all do that 'shadow ground tap'!) in certain hands and less others: Pick-up preference is pretty much universal IMO/E