EPTA 111 Terran build, imo doesn't cut it, because any protoss opener *has* to include super fast stalkers. A 111 will put the Terran behind with any kind of early stalker harass, even if the Terran pops up a bunker.
However the threat of early reapers and the ridiculous strength of a 3 rax bio build,with/without ghosts, forces the protoss to gear up a certain way and they cannot expand until they hold off the bio push. Now any 400+ diamond protoss has to have learned how to hold the first push, but it's such an effort to do, and it gives the terran the opportunity to expand first and get an economic lead. 3 rax isn't an instawin (although, at low diamond and below it usually is) but it forces the game to a certain way. And it's impossible to force it to go any other way AND survive the opening push.
Now void rays can help, there's a small window just after you've held the 3 rax push where you can go on the offensive. But the typical followup to the 3 rax is to hold with marines, and then pump out 3-4 vikings. The flying siegetank then shuts the window and the Terran is ahead in macro and from there has initiative a solid defense and an economic lead.
So it comes down to a battle for expos, and trying to find a chink in the terran turtle. While being vigilant you don't take a massive hit from a drop yourself.
Sadly attacking a biomech turtling terran is a bit like Russian roulette, where the Terran gun only has one bullet, but yours has 5.
Protoss can't just sit back and defend because if 5-6 tanks rock up out the front it's already gg. You have to engage Terran in the open and on the move.
