Those larger bass were preying on the stunted bass and now they don't have as much to eat. Might as well remove them as they won't ever recover.
You may be able to do supplemental stocking of BG too big to be eaten but that's beyond my experience. Mostly you're just gonna have to wait for things to swing around. It took years for that pond to get into that state and it will take a few years to fix it up the way you want it. I started out where you were and the culling has definitely paid off. Click below for some proof
