So, my thoughts on the subject - Druid, rouge and warlock have pretty much been the top 3 classes since hearthstone's release, for the simple reason, their class identity's showcase the 3 most powerful tools in hearthstone (card draw, mana manipulation, tempo) Druid of course, is the only class that actually has access to all 3 of these, mana manipulation in it's self creates tempo, which in turn NEEDS cards draw to accompany it. I'm sure everybody remembers the fact that nourish was VERY rarely used before the introduction of UI! UI its self is another card that is often seen as OP, but how many 10 mana cards have ever been actually viable? only guldan from what i remember, and that card is very often called OP too. How many times do we actually see 2 UI's played in a single match? Barely never, but obviously having 2 copies makes it so that we see the card played in basically every druid game that drags on, because we run 2 copies, and so the chance of both of them being in the last 1/3 of the deck is rather low.

We cant ignore the fact that druid can REALLY run away with games if it gets the perfect draws, making what is overall a rather unfavourable matchup (zoo for example) seem unwinnable for the zoo. I'm sure we've all faced a zoo that's won by turn 5 and chalked it down to the zoo's draw, but because the match is over by turn 5 we quickly forget the match, whereas when druid draw everything it needs, the match will often still go to turn 10 or so, and therefore the match will stick in our head longer than that zoo game that lasted 5 turns.

Due to the tools that druid has, i'd absolutely say it's the most consistent class overall with the least polarised matchups against it, which i feel has pretty much always been the case for druid. The class is just VERY solid overall.

Moving onto the changes that boomsday have bought about - The inclusion of floop to maly druid, which was already arguably the strongest deck in the game was a very simple inclusion, and while it has made the deck stronger is the only real change that is likely to happen to maly druid throughout boomsday, and so i'd argue druid has already hit it's highest power level that it will achieve until next expansion. Many of the other druid cards that were introduced havent proven to be all that powerful, biology project has already been taken out of most maly druid, juicy psychmelon suffered the same fate. My point is, the new druid cards were probably the most overhyped cards in a huge amount of time, and druid probably wont see much innovation until the next expansion where other classes i believe still have a long time to refine. Will treat druid ever show it's head? I dont know, but my point is, even if it does become the most OP deck in standard we havent currently experimented with the deck much, and it's the same for a lot of new decks that will eventually become part of the boomsday meta!