One thing I ws going to say, but I think Tom has beaten me to it, is that some of the claims on here seem to be tarring all pro's with the same brush.
I bet there are some pro's out there who are bat geeks like us, and won't use anything that is .1 of a gram too heavy, that doesn't have exactly 39.2mm edges, and must have atleast 10 grains that are no close than 3mm together but no further than 6mm apart, and moisture content must be exactly 7.6%, and the willow must be exactly the same colour as dulux desert wind 2.
That bat is probably quite hard to buy off the shelf..
But then some test pro's will just get a bag of bats sent direct from the factory, and they'll pick them up and use them in the nets, and keep the ones that feel right