If your build can be "beaten" then you picked a gimicky build which I did not encourage. You will notice that almost every masters players gives the same advice that probes and pylons (or scvs and supply depots) win games. It isn't to be malicious, it's because that is the foundation that every other decision, micro trick and army composition is built on and even when a player hits masters that is still where the majority of their flaws will be. You might think its unfair that people are judging your play without seeing it, but if your mechanics are really up to it you don't need to coach to get to masters. You just need to play more games untill promotion.
Your point is that core mechanics such as your mechanical execution and solid openers is the foundation - this I agree with.
However, while I would fully agree in WoL, there is no HotS build that cannot be beaten on every map. This is why the meta-game is always changing. Blizzard has seen the stagnancy of WoL, and made balance changes that would promote aggression or map control - diversity. They have stated this to be their intention from the beginning. Even top professionals change and prepare builds specifically for certain opponent and their signature builds. So I am unable to agree that mechanics is everything or even most of it. Mechanics can only do as much as your strategy and understanding of the game; vice versa.
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