MM at least shows what items actually sold for, and not just what a seller listed them for. TTC isn't always a good representation of the market, because it can and has been used for....misrepresentation...shall we say.
It is down, and this highlights how much ESO needs a universal shop search built in. It's just not practical to buy or sell without it. I do not have the play time to visit 900 guild stores to see what the average price of something is, or hunt down that thing I'm looking for. It's too absurd. There's Master Merchant but that only uses guilds you are in and isn't a good representation of the market.