Wow, that's a huge piece, and it looks really cool in that last picture!
It looks like there is zero tissue between polyps - if so, you're correct, that's typically water conditions. When water conditions get really bad, each polyp basically decides to act on its own, and it cuts ties with its neighbors (every "polyp" for himself!)
With good water conditions, the polyps should start extending tissue again. This often makes for weird growth patterns as the new tissue growth will try to make new polyps where existing polyps are. Nothing harmful, but it can look odd for a bit.
The polyps as they are look really good...they should make a full comeback, especially with feedings and good water conditions.
Good luck!!