Comment by elchupanebre

The reason for that is actually rational: when Amit Singhal was in charge the search rules were written by hand. Once he was fired, the Search Quality team switched to machine learning. The ML was better in many ways: it produced higher quality results with a lot less effort. It just had one possibly fatal flaw: if some result was wrong there was no recourse. And that's what you are observing now: search quality is good or excellent most of the time while sometimes it's very bad and G can't fix it.