I've been either Balance or feral on my Druid since WotLK; I decided to try Resto out again for Legion. I've only ran two dungeons so far; one went "ok" and the other was a bit of a struggle but we managed it in the end. I don't know if I'm doing fine and the struggle one was because of a poor Tank, or if I'm doing poorly and the ok one was because of a good tank.
My question to the druid community is...do the proving grounds actually help with solidifying your healing; or do they at least give you a good indication of how you're doing as a healer?