The match between Stockfish and AlphaZero was played with certain unjustified parameters (time control, ponder off, different hardware, no opening book or endgame tablebase for Stockfish etc.). By "unjustified," I mean that the authors of the paper did not justify their choice of parameters in the paper as being designed to implement a fair match.
At a glance, the parameters of the match seem unfair to me -- and tilted heavily towards AlphaZero. If the code, were open source, this would not matter; anyone could run a rematch. As it is, I haven't seen any convincing evidence that AlphaZero is stronger than Stockfish when Stockfish is allowed to use its full breadth of knowledge and run on equal hardware.
At a glance, the parameters of the match seem unfair to me -- and tilted heavily towards AlphaZero. If the code, were open source, this would not matter; anyone could run a rematch. As it is, I haven't seen any convincing evidence that AlphaZero is stronger than Stockfish when Stockfish is allowed to use its full breadth of knowledge and run on equal hardware.