Playing a deck with no chance to discovery is mechanical and luck based.
For instance, I have a Protoss Rogue deck, which have a good winning rate, but I really don’t find it fun, I’d rather play Protoss Mage because you have so much opportunity to discovery things, even tho I lose much more often.
For instance, I remember a game against a Armor DH (on it’s peak), that I won with Protoss mage (almost impossible) because in the end I decided to Discovery a Druid card with Sparkling of life and got Hydration Station which brought my Ship back, which was copied from him with “Buy one get one free”. Both os those cards were not in my deck, but with discovery you have the change to adapt to the current match. And how about when you get (1) Bran Bronzebeard into Colossus?
Many times when all my Colossus are gone and my opponent is still alive I discover Supernova and get some good finishers.
Now I’m having fun with Protoss Imbue Priest. Really bad deck, but very fun. I love the Imbued Priest power, I just wish it was a little bit better, for many times I hero-power just to find out I have no mana to play anything. It’s a waste of 2 mana that I could have played another thing. And many times I have a lot of discount and a lot of mana just to be shown two low cost cards that have no impact late game.
I’d much rather have the Imbued Hero power: Discover a Priest card, reduce it’s cost by X.
At least one more option, I don’t care if it’s minion or spell.
EDIT
There was this game, on of my most memorable wins, I was playing Galak rogue (I believe) against a Wishing Well rogue. He got his Well down and I couldn’t kill it, so he started doing his shenanigans with his coins, I had a Vanish so I decided I was going to let him build his army. The game went on and he kept his shinanigans, playing coins, legendary minions, and drawing a lot. Then at some point I was prompted to discover a dragon and saw a Nozdormu (15 secs for a turn), that’s it, I choose it and hard pay for it, You could see how desperate he became trying to play so much stuff in one turn, and over-drawing a lot at this point too. He eventually killed it. As the game progressed he played a legendary that brought Nozdormu back and the fuse started to burn, he conceded.
I would never run a Nozdormu in my deck, but with Discovery you can find some answers for a specific match that wouldn’t dream of otherwise.