1. One of the maps is 2nd voted from last week,
2. Another of the maps is highest rated map with at least 10 ratings made between last 2 and 9 days
3. Another map is from "random" category, any map which hasn't been in map of the week before and has at least 3.9/5 rating goes to this category
4.-5. I guess someone believed that the other 2 nominated maps can either win or come 2nd in this week. What is and isn't a good map is a subjective thing, so maybe those 2 maps are really the best maps, which suit the preferences of the players the most.
I think the Asia and a Dance with dragons are the best maps and they were not directly nominated, so not much could be done about that.
Why did MOTW jump from week 270 to 273?
I presume that some bug happened.
Edited 4/3/2020 15:30:59