Balance Druids have a weird issue currently. They have amazing AoE/Cleave OR Single-target.
Their talents are very clearly cut between those 2 styles, meaning if you go for an AoE build, your ST suffers massively, same thing the other way around.
This tier also has not had the best design. Tier bonuses are only based on ST, so they do nothing for AoE. This is however fixed in the next tier with better bonuses overall for ST and AoE(I would go as far and say the new tier bonuses are insane for the Emerald Dreamcatcher Legendary).
Overall if you are using ST talents on a ST fight with Emerald Dreamcatcher, you will be in the upper part of the DPS meter unless your raid is stacked with high skill rogue/DH players.
DPS aside, Boomkins have a lot of utility through their abilities and talents, which every now and then make them extremely potent for some fights where CC is needed. Innervate, mass root, single target root, AoE pushback, Blink/Disengage(they are in the same talent row), AoE silence/interrupt, 5s ST stun, Battle ress, root/slow break.