Except for Crabrider, none of these nerfs is actually relevant imo. The nerf to Hysteria is a freaking joke.
1st Day of School is not even a real nerf actually. Paladin will still win everything in standard and it's boring, shaman still sucks, Frenzy still sucks. And Refreshing Spring Water is still way too good in spell mage. Hunter has received no changes at all?
The buffs are mostly irrelevant. BG might become a little less one-sided, but that's it.
On a sidenote: WIld and Duels are close to unplayable right now in higher ranks, but who at Blizzard cares anyway.
Just my two cents.
This paragraph gets written EVERY single time there is a balance change and it almost never ages well. Single mana nerfs are a big deal and they continuously affect the meta whenever they are introduced. Hysteria - for example - is a card which has become more and more problematic as it has proven to be WAY too efficient of a board clear for a relatively cheap cost and when you combine that with the high potential for discovery in Priest decks then you are left with an extremely frustrating situation where one player is continuously punished for attempting to establish any board control. Allowing a player a single extra turn to establish board presence and do potential damage while robbing a Priest of 2-4 mana per game (depending on discovery amount) is absolutely a big deal.
Can't play it with Kazakus too.
Pretty good nerfs, the Mankrik one is a bit out of place.
Buffs are okay, although some of them are completely useless.