I think the standard between the top4 including MbL is so close. Hera played really well, but Liereyy is such a genius of this game unfortunately. He has made such a huge progress over the last few months.Personally, I don't consider Liereyy's win over Hera to be a surprise as I think Liereyy was always the favourite. Whenever he has trained for a tournament (meaning he plays some AoE befor the tournament instead of just appearing for the tournament games) he has crushed Hera. Not only is he the finalist for both KOTD and KOTD2 but also he recently won to Hera in RBW2, so no surpises here.
It has also been stated that "any of the four" would have reached the finals were they on the other side of the bracket, and I consider that not probable. Had Viper played with the level he showed last Sunday, he would never had been able to beat MbL. Let's remember that MbL has been playing extremely well this tournament, that he beat Yo and that he has beaten Viper several times in the past.
also Yo in his stream said Viper actually didn't make big mistakes, and said he played pretty well, it just happened that he could correctly forecast viper civ pick and play the right way by the civ advantage. Also game 2 its too freaking unfortunate for Viper, the worst map I ever seen since I played the game.
And yes VIper no longer dominate the game, but he is still a competitive and great player, which is good for the overall development for AOE.