Petr has an average curve in the first game: Veteran Armorer, Civic Wayfinder, Fist of Ironwood and Diverbomber Griffin. That is not a great curve for a typical Selesnya deck, as it lack a lot of aggression. After Sam resolves Drift of Phantasms, transmuted for and played Vedalken Entrancer and summoned Tidewater Minion, Petr never ever got to attack again. Later on, when yet another Entrancer arrived, Sam was milling six cards a turn, and Petr never stood a chance.
Game 2 was much more of the same actually, a Elvish Skysweeper was killed by Clinging Darkness, Stinkweed Imp and Drift of Phantasms held Civic Wayfinder and Divebomber Griffin at bay, and Vedalken Entrancer made sure Sam would never lose. While it is true that Petr drew some more lands than he needed in the second game, I don't think his deck is aggressive anough to stand a chance versus a good Dimir deck.
Sam wins 2-0