Originally Posted by
elfporn
They clarified the way they drop a few times after launch, once when droprate was bugged, and then to clarify the fix, and then when they were caught in a lie.
Originally, on launch, it was supposed to be opposite of what you've stated, you were supposed to get your 2nd, 3rd, 4th, faster than the 1st, and after 4 bad luck protection went away. The launch version of the drop system was scrapped because it was bugged - people were getting 2, 3, and 4 legendaries within days of getting their first. This was fixed fairly quickly.
Afterwards, they kept the drop rate and bad luck protection the same no matter how many you had(same as 0-->1), but left in place the 4th legendary ceiling until they were called out for it. The legendary ceiling is now gone, and your bad luck protection resets to base each time you get one, how many you have does not affect bad luck protection at all.
The system never, at any point, worked the way you describe - all this information has been handed out by blizzard at different points in time. The open letter to blizzard penned by one of the top guilds is where the 4th legendary softcap issue came up, posted by mmo-champion.
Getting a legendary doesn't reset the drop chance to 0, it resets it to the base drop chance which has never been specified. You are still able to get a legendary even at the base chance.
The data you linked might not be wrong, but it's a very small data set. The system is still rng based. People still get their 5th legendary and then a day later get their 6th (happened to my fellow rogue).