Did the price actually go up pre-fork because some thought they would get a new coin out of this? That would explain why price is going down now(no new coin), I mean the fork was a success so price should be rising.
No, anyone who follows Eth knew it was only a hard fork, not a chain split.
Market price is volatile. It's not a perfect 1:1 correlation to how successful the tech is; certainly not within a timeframe of a couple days...