Well, like I said to Paul...I have no issue with comparing an INDIVIDUAL season to the appropriate climo period...for instance, 1978 to the 1951-1980 period, etc....or 2018 to 1981-2010. However, for a composite of seasons from a myriad of different decades, I prefer the expansive 1951-2010 set.
No, I don't expect normal temps for the south as a baseline la nina composite, however, perhaps a certain individual season will turn out that way....which is why we look at a plethora of other variables.