I've just replayed them as well. You can see that in the first game the bot played really solidly without risk-taking and didn't want to lose even a few stones

I've just replayed them as well. You can see that in the first game the bot played really solidly without risk-taking and didn't want to lose even a few stones. You could say that it played very conservatively but solidly. It won by a tiny margin (2.5) so Fan Hui probably concluded that the bot would win every game by a similar small margin if he didn't change the style of play. I'm sure that in the first game Fan Hui was sounding the bot out for strengths and weaknesses, seeing if it knew all the tesujis and josekis and whatnot. So from then on you see Fan Hui trying to mix it up and play more aggressively and what is very interesting is that he got outplayed in every game, even to the point of losing a big group and resigning. So - if you play conservatively and tentatively and solidly it'll beat you by a sliver, if you try to out-think it it'll nail you. At least at the 2dan pro level. I'd be hesitant for calling a Lee Sedol victory ahead of time. We know that in chess Kasparov beat IBM's bot initially but then IBM tweaked and within a couple of years the bot was too strong. Even though go is much harder than chess I predict that if Google lose this time and if they don't lose by much they'll win the time after that.