So we have 5 nerfs and 10 buffs incoming. There are 2 neutrals included in the 5 nerfs, one of them being a Murloc.
I expect Crabrider to go to 3 health (or maybe a 3-mana 1/5 or so?), but I'd rather see him receiving a different kind of nerf that will make it more board-control oriented: 2-mana 1/4 with battelcry: 'Gain rush and windfury this turn'
Called it on Crabrider and I'm very happy with this nerf. It really doesn't kill the card,especially in decks like Rush Warrior that care about fighting for board control, while at the same time it cannot do silly things if it survives for 1-2 turns. It sucks a bit that it won't gain windfury if summoned by other means (Tip the Scales or Call to Arms), but you can't have it all.
As for the other nerfs, Hysteria will probably still see a ton of play at 4 mana which means it was probably a bit too good at 3-mana and thus deserved the nerf. On a side note I really like this card as it rewards skillful play both in terms of using it and (more importantly) in terms of playing around it. Regarding Spring Water, I know everyone expected (and wanted) Incanter's Flow to get nerfed instead, but I am fine with nerfing RSW instead. No Minion Mage needed to be toned down a bit, but I think that Flow to 3-mana would kill both the card and the archetype (together will all the APM Mage archetypes in wild). Finally regarding 1st day of school, I have mixed feelings about the 'nerf'. For standard paladin decks, it is only a nerf in aggro mirrors where you can no longer consistently have an 1-drop to play on t1 (and curve into a Hand of A'dal naturally for example), but in matchups that might be a bit slower you now get a bit more value/refill which can be a plus. Also Handbuff Paladin says thank you