I suspect the fish would have moved to the deepest part of the lake when the water level went down. This location may or may not have been a "hang out" for them prior to the drainage since they had other cover to hide in.
I'm not so sure the grass and weeds that grew in the dried up area are going to have that much of a negative impact, unless of course it has all died out and turned the bottom into a thick bed of slop.
The bass would have gone back to their normal habitat when the water level went back up, or at least move in from deeper water to feed on baitfish, which I assume are probably minnows, bream and bluegill.