I used to think this card was a worse version of that 2 mana spell from the Boomsday that I don't think even saw play in Mech Hunter to begin with, but I've done some thinking and changed my mind about this card.
Think about it. Firstly, it gets discounted by Mechwarper and Galvanizer. So you realistically won't be spending 3 mana on it. Plus, it has 4 health instead of 3. Now why is that so important? Because with 4 health, it survives against Hellfire, Flame Ward, Arcane Flakmage, Ziliax, Medivh's Valet, Frostbolt, Torch, etc. Not to mention that it also works against Defile
That means that this will add tons of Mechs to your hand if your opponent uses Hellfire to clear your board. It means that if you play this before you attack a Mage hero, their Flame Ward will add more fuel to your hand. It means that if the opponent wants to deal with this, a Warlock would have to waste a Mortal Coil on this before using Hellfire. It means that a Mage would have to use their hero power alongside wasting 3 damage card to remove it.
Even if the card gets killed before it can generate any value, it still forces the opponent to waste their turn trying to remove it.
I think this card is enough to make Mech Hunter a tier 2 deck or at least fairly close to being teir 2. The only thing standing in Mech Hunter's way is Even Shaman with their Devolves.