There is too little inter-region play in D-III to have seriously valid "RPI/SOS" numbers to seed at this level. This is not like D-1 hoops, where the top seeds may have played one another in the regular season.
UMass-Boston was the #7 in New England which is highly respected as a region.
UWStevens Point was #4 in the Midwest; no slack region either.
Heidelberg looked vulnerable going into the late innings against #5 Adrian, playing their second game of the day.
The seeds are set at the beginning of the tourney. In a double-elimination, you have to win them all.
Frequently the finalists have settled the question, best 2 out of 3.