I have hit the last two Melbourne Cups with non-favorites (Dunaden in 2011 and Green Moon in 2012). My approach looks at two factors: weight carried (114 to 123 pounds) and recent race activity in Aussie.
Here are my Melbourne selections (in order of preference):
(1) #8 Dandino (2) #21 Verema (3) #15 Mount Athos (4) #23 Tres Blue
I will note that Verema and Tres Blue lack a recent Aussie race, but are largely considered the best two horses. in the race. Fiorente had a very tough run in the Cox Plate and may well regress off that effort.