#1 - Aug. 12, 2013, 3:31 p.m.
I'd like it to be deck-based, but the question then becomes what qualifies as a deck? Sure, if you start a new deck, it'd have its own MMR under that system. But what if you replace all the cards from one deck with another? Being limited to the same hero might constrain some of the more abusive aspects, but it'd still be problematic.
Bottom line: I'd much rather have MMR based on each individual deck, but there are a lot of practical issues that would have to be resolved.
Thoughts?
Edit: Changed title from "Deck" to "Class." Class seems like clearly a better option.