My first thought when I saw this list, was: "Woah!! That's a blast from the past!"
I have not seen a Tezzeret-based vault/key deck perform well at a large event recents. I'd suggest that there are a few reasons:
- Creatures are everywhere; reducing the value of Tezzeret
- Null Rod and Stony Silence see a decent amount of play
- Mana Drain is a little slow when put up against Arcbound Ravager and Monastery Mentor
- Swords to Plowshares and Dack Fayden are best buddies with Blightsteel Colossus; but poor BSC always feels like the other cards are ganging up on him...
In game 1, the lack of removal (either permanent or creature), would hurt, as other decks are much faster (for example, any deck running the Paradoxical Outcome engine).
The transformation is cute, but I feel like it leaves the deck somewhat soft to taxing effects, and dredge. A Smokestack-based deck that deploys a Null Rod and some spheres effects, then follows up with some land destruction would be difficult to beat with 15 lands (one of which is colourless, and two of which would be shut off by the rod).