You're thinking of Pillar in June, but the two really aren't that comparable. None of Pillar's peripherals changed during that hot streak, in fact he actually posted his LOWEST walk-rate of the season during that month, and his third highest strikeout rate. The conclusion? He was doing the exact same thing he always does, which confirms that he was simply "hot" and/or benefiting from luck.
This Goins thing is different because his BB% post All-Star break has been elite; going from 5.7% to 16.5%, which shows obvious improvement at the plate. What are the implications? The significantly higher walk rate means that he's seeing more pitches per at-bat (thus increasing the likelihood of seeing a hittable/poor pitch), and it also means that he's being more selective at the plate, which will naturally indicate that when he does swing, its at more hittable pitches because he's doing a better job dictating the course of the at-bat. All of these factors realistically contribute as a possible explanation for why he is hitting significantly better, apart from it simply being a fluke hot-streak.
I'm not suggesting that this is something that will continue long-term, but plate discipline isn't exactly something that you can "luck". It also isn't a skill that is generally seen as teachable, which is why Goins is going to be a very interesting case to follow in the future. Mechanical changes to a swing can however "unlock" plate discipline. His 16.5% BB rate post All-Star break is 5th highest league wide, so he's not just been "good", he's been very good at drawing walks.