WOGL, from an 8.2 (first place), down to a 6.8 (4th place) since July 2018. Should have left the 60's and 70's music alone. Return to the way you were and things will improve again.
As has been stated many times before by may radio professionals, "these are meaningless 12+ numbers" that don't even get looked at by time buyers and the stations themselves.
As long as WOGL is in the top tier of stations in 25-54, they will get on many/most ad buys.
As has also been noted many times, ad buyers who use ratings look at multi-book averages, not just the last monthly book. Often they look at the last 6 months or more. So the little sampling wobbles and seasonal differences are flattened.
And, finally, agencies and big advertisers look at rating and not share. A 1.2 share point variation is reflected as a 0.1 rating point change. So those "apparently big" changes in share are not visible when rating is used as a buying criteria.
On the programming side, WOGL has been trying to shed the older listeners to be better focused in 25-54. When stations do this kind of "trimming" the 12+ will often intentionally go down, with a simultaneous increase in 25-54. In other words, that is a very good thing to have happen.