I believe that our Fish and Game has determined the average California black bear to weight about 225-250 pounds. As to the average weight of one harvested, I don't have any figures, but would guess it to be a bit less than 200 pounds.
I would take exception to the attempt to characterize those who tag small bears as being unsportsmanlike. For one, in some states or regions of a state, the bears do not gain much size or weight as they get older; the limited feed simply does not allow for much growth. Secondly, it is not contrary to the overall health, survival, or prosperity of the bear population to take the younger or smaller animals...actually, more the opposite. While I personally prefer to leave them in the tree no matter their size, it does not concern me in the slightest that another hunter may want to tag a bear that is more tender or easier to drag out of the woods.
California does not allow for the cubs of the current year to be taken, and prohibits the killing of bears weighing less than 50 pounds. I certainly this is a reasonable stipulation.