I am not so familiar with SC2, but I know a bit about BW. I think you are mystifying Flash a bit here. I went through a BW phase (because my friends were all interested in it). I was trying to learn a build, so I watched Youtube videos of Flash games where he goes siege expand vs. Protoss. When the camera shows Flash's scout exploring the enemy base, you can see what information Flash gains, which is a (possibly incomplete) count on a number of units and buildings. Then by Flash's actions and deviations from his usual build order, one can construct an if-else statement of his reaction (defined as deviation from his standard build).

For example, one detail I noted was that he usually builds an Engineering Bay on 33 supply, but one game he starts it immediately at 21 supply after his scouting SCV was blocked by zealots from entering the Protoss base and seeing no Nexus up at the natural. The reason he did this was because he was afraid of 1-base DT rush. This gives us one thing that Flash looks for when he scouts in one particular build vs. Protoss. Since Flash is but human, I believe his thought process can be reduced to a checklist. It's not a very romantic notion of the best BW player of all time, but given enough data I believe it can be done. Perhaps by a bot that collects all the data from Youtube videos of pro BW games. I was thinking of writing a bot that does that, but what with the declining interest in BW and having to learn new tools never got around to it. Or even better, a former pro player could be asked.

There are fakes in BW too where a player begins construction of a building while the scout is there, but cancels as soon as the scout is out of sight. This would be included as part of the data, which a clever enough parser would be able to make sense of.

> and he still loses a lot from being too predictable, too routine, producing the same responses to the same stimuli - even though his macro mechanics and builds are utterly top-notch.

I think at least part of this may be attributed to the difference in mechanical floor needed to play the game at the top level. In BW, the number of players who could keep up with Flash's late-game macro were a mere handful. He had a reputation that even if you knew what he was going to do, you still couldn't beat him. In SC2 however, the reward of predictable play going to late-game may be less apparent.

> For me, the mechanical things are a zen thing. It's almost like a sort of meditation; your mind falls into these practiced routines, but you have to juggle all of them at the same time, choose which ones you can afford to let fall (since you can't do everything at once,) and then have your higher order tactical and strategical decisions on top of it. I haven't ever done anything else which engages my mind in the same way, and it certainly wouldn't do so without the mechanical demand you can never truly fulfill.

This part is quite fascinating to me, because I recently had a similar experience playing Osu!, which is like fast-paced DDR but with mouse and keyboard. At first I was just clicking slowly, but after several hours, I felt my body taking over and almost playing the game by instinct beating maps that were way too fast for me to beat a few days before. Before such an experience, I'd dismissed people who play Osu! as wasting their time doing something pointless and the music as a great destroyer of conscious thought. Yet after getting into a relaxing "Zen" state similar to the one you mentioned, I felt I could still think very clearly about my day, which came as a pleasant surprise.