I run into a lot of peeps on ladder who loves to go 12 gate, cut zealot, steal my gas and get their own gas and also start mining from it, regardless of my opening. They make up for the delayed WG this causes by having sentries at their ramp to prevent 4gates while they do some greedy 1 gate robo variation.
In this build the pylons get placed when there's only one sentry in those kinds of builds (4:55 smtn) and your opponent HAS to forcefield to not have a pylon in his base and die. While the forcefield protects him a second sentry will pop with it's own forcefield but that wear off around the time your WG finishes. And it's pretty clear how 4 stalkers+zeal does against 1 stalker and 2 sentries .
a note: in Oz v sage Oz cancels his 24th probe and immediately remakes it again to "fake" non aggression, as sage otherwise would've been able to see that he cuts probes to get the gates up faster, I found that kinda cute I dont know if it's worth the hassle in a non GSL-environment though, this build seems to work well for you even without optimal excution...
A question as well: I think Oz used this build because sage seemed reluctant to get a zealot before stalker.
In game 1, Sage HAD to get a zealot because Oz went with a chrono'd zeal before core so not much to say there, but he skipped it in game 2, and skipped it in game 3 as well (and even though Oz didn't know this he might have known sage's tendencies, and judged that he was likely gonna cut it out). Is it possible to get the 2 offesive pylons down by your opponents if they have both a zealot and stalker to zone your probe away with.
Do you think that you can get your proxy pylons set up close enough to make advantage of your earlier WG timing if your opponent gets a zealot+stalker and uses it to zone out your probe? Even though your opponent does this in the 3rd replay it doesn't seem like he even tries to look for standard proxies.
nice write up