Yes you can do it, I did it a few times, but it has to be something people overlooked entirely. And that means it’s probably not as good as the true netdecks, but you bet on people being unable to predict whats going on.
I never play pure netdecks, but often netdecks with a twist so to say, the strong structure remains intact, but you change the focus of the decks.
I believe to be the originator of odd elemental rogue back in Witchwood, and Wild Patron back in BRM days. Thats entire different focus, mostly I often add some cards and remove some. For example Galakrond rogue I let go of the stunners and the entire secret package, though more ppl did this.
Often you would see ‘deck doctors’ back in the day on twich, when this game was more popular. Often it was a matter of adding patches plus a few pirates, or take those out and add something else back in. That’s cheating, it doesnt matter, and subjective to meeting a slightly lighter or heavier meta at that moment. Couldn’t call that deck doctoring.
All in all I made some unique decks, suitable for countering pivotal metas, with above average results, I believe.
Back in ONIK, when everybody played tempo shaman, made an anti-tempo shaman deck, got like 74% winrate out of it. This was also an unique deck and not a variation of something, I would guess my biggest achievement.
Made a strict anti aggro priest at some point where everyone was agressive, maybe Mean Streets, 72%.
Got a few 60% decks in the original classic and lately in twist that were strictly off meta.
But the game is now so ‘locked’ into having to take certain packages that it has become clear to me its probably not possible to build something good that is different from what is intended by Blizzard.
My last own deck was a greedy rogue that focussed on the omnipresent hunter with their OP spells that created the 3/1 rusher, 2/5 taunt and so on, forgot the name. That greedy rogue deck sucked and I only got 51% out of it or so. Haven’t tried since, though did get a very good deck in Twist.
Only mentioning legend decks.