No way, it's debatable that it's actually MORE than 90% skill. Give me GG vs a bad player who has the exact same GG list. I guarantee I'll win 9/10.
Chuck: You just made the opposite point than what you were trying to make.
Sure, give each player identical decks and THEN it's 90+% skill.
But that's because you took the deck variability out of the equation.
How important is it to HAVE that GG or whatever top tier deck?
Could the best player in the world with a PCD beat an average player that has a GG deck?
Maybe, but I think the average player would win most of the games just because the deck does play a large part in it.
A well built deck gives the player options.
A crappy deck gives no options, regardless of how good the player is.
So, sure, skill is a large part of it. Especially when that skilled player is armed with a good or great deck. But you can't discount the contribution of the deck.