I'm having a bizzare grouping of search results by domain with no apparent attention paid to relevancy.
I'm not sure how long it's been going on, if it was only after the last update or even before this.
Essentially I have several sites walked from a few profiles, and have all of them searched through a meta search. The results are grouped by the domain of the results, and certain domains appear first regardless of the relevancy score of the results (74% highest result domain with 71% results appears above a 76% highest result domain). Additionally, it seems that the domains appear in the order of the size of pages indexed.
The rank knobs were not the same on all profiles - do they have to be? I was under the impression from the documentation that setting custom search metrics for each profile was an option.
To test your question, I created a new meta search, and pulled in only the two largest profiles, set the rank knobs the same on both of them, and tried an advanced search, and the results were the same - the largest profile (most indexed pages) had all relevant results shown first, with the other profile appearing after - again regardless or relevancy.
The backend rank knobs don't matter. They may be different across profiles.
The problem has been found in the latest update (scripts 6.1.2) and a fix is on the way. Unfortunately there's no workaround. The meta results are grouped by profile.