I actually think this is the exact wrong answer. Balance is not the main problem with arena. There are balance issues, sure, but the problem is that the changes over the years have led to gameplay which is far too scripted to be fun.
More viable comps, more balance, these are red herrings which we as a community have tried to chase for way too long. Arena was great even when only a handful of comps were viable, because the comps really played dramatically differently. Making everyone the exact same and then proclaiming that every comp is viable is a pyrrhic victory.