A theory floating around Reddit has is that HBO’s Westworld actually exists in two timeframes, past and present, and not in chronological order as it appears.
William and Logan’s timeline occurs in the past, presumably shortly after the park opened. while the man in black, and all the Westworld employee scenes happen in the present.
There’s actually a growing body of evidence for this theory, compiled on /r/Westworld.
And this video from The Outline does a great job at laying out the facts.
Here’s some of the evidence.
1. Characters in the two timelines don’t run into each other.
William and Logan never appear in scenes with the man in black, Teddy, and Maeve, the madam of the brothel, despite the fact they all appear to be in the town of Sweetwater at the same time. You do see William and Logan with Dolores and Clementine the prostitute who are older robots who tie the timelines together.
2. The Westworld logos are different in the two timelines.
Also in the present timeline, when the employees venture down into the old abandoned part of underground facility, you can see the old logo.
3. The milk cans are different.
In the past timeline, William picks up a can of canned milk that Dolores drops. In the present Teddy does the same. But the fonts of the two cans are slightly different and the past can has a space between maiden and brand.
This theory sets up the possibility that William is the man in black, but 30 years younger. Something in the past triggered William into going nutso and dedicating his life to the maze puzzle. But that theory is far more speculative.