I've managed to reliably beat strings of 2/3 Thunder stages with my 1/4 complete Water team since the debuff duration fix, at least 3x so far. I imagine it'll only get easier once the +100% eidolons release. It's a pain right now because the fights take a while and I'm still running Sol and 2 Water SRs. Try a Fire team with only a single Fire SSR and no Belial, and I imagine Rank 4 fights against Water wouldn't go so well.