Can't say for sure, Lin, but if you consider that 2-3 years back, there were hardly any flatties of any size to be caught around the southern inshore waters, then the fact there are now heaps again is a positive sign, I guess. As to there being such a big proportion of littl'uns, it may be that the waters where you are fishing have been fished pretty hard already over the summer, so size fish have already been removed. IMAS recently released results of its rec angler survey that showed flathead is by far the most popular fish caught: around 1.7 MILLION taken last season around the state, with around half of them returned to the water - the biggest part of that effort was in southern / south-eastern waters.
I guess we must just be patient and let the huge numbers of juveniles get bigger - next summer (or the one after) should be excellent!