Another master piece by blizzard, they finally give the new decks in the brawl, the standard decks. All your cards are standard ones.
But guess what? You can discover wild mechs because they forgot to restrict it to standard cards. Decks with discover can be busted if they luck out. RNGsus.
Hasn’t Tavern Brawl always had access to the entire catalogue of cards for purposes of discover and deck building? We have recurring nightmares like the Pogo apocalypse brawl every few months.
It’s a fun little brawl. I hadn’t even thought of your main point, seeing as I play wild and see those mechs every day. Seems normal to me 
I actually noticed this, too.
The discover options were leviathan, Blingtron, and Mecha’thun. Clearly not standard pool.
Yes, mech mage was an easy win. Now I do not have to play it for the rest of the expansion.