This is the expected behavior. There's nothing special about
mlb.com. Same happens with any other domain with more pages accessed by the user.
The feature works (mainly) by putting in front of the user the most visited URLs.
In this case from what I understand you probably accessed 4 different pages on that domain. Each counts as a separate entry in our db and each entry will have it's own number of visits counted which allows sorting them and showing only a limited subset of the total entries.
IMO this is not a regression because as Eliza said, before my patch, each visited page (even on the same domain) would appear in that TopSites list and in your case you would still have to press remove 4 times to actually remove all
My patch just grouped together all pages for the same domain to allow for other domain to appear in that list. If you remove the most visited page on a domain, the second most visited would be shown and so on.
Don't really know if we should drop all pages from a domain. Some might be bookmarks, some pinned, others just history entries.
Asking for Devin's input here.
Type: defect → enhancement
Component: Awesomescreen → General
Flags: needinfo?(petru.lingurar) → needinfo?(dreams)