Between all the time shenanigans that are being speculated about for the new content, it just led me to think the following.
We know S4 starts with El's letter to Mike saying it's Day 185. Then it's March 22, which is, of course, Will's forgotten birthday. And Vecna's first kill happens at the same time.
But Day 185 actually takes us back to September incorrectly, as fans pointed out. Following the ending of S3 on the 4th of July, and then three months later when the Byers move to California, 185 days would place us on April 7, which is canonically Mike's birthday.
April 7 is also important because it's the same day Vecna's fourth sacrifice would take place, with Max surviving in the cemetery in Lucas' book, Lucas on the Line. An obvious timeline change to finish Vecna's ritual.
And yes, I know these books are officially considered soft canon due to all the inconsistencies, but similar inconsistencies have also been found in the related merch and other marketing materials. One is a coincidence; two is a pattern.
So Max is saved by Kate Bush while the famous lines are sung: "And if I only could I'd make a deal with God And I'd get Him to swap our places..."
And the next thing we know, in S5, Will and Mike swap the watches on their hands, and all the marketing materials states Mike was in the Upside Down, not Will.
Maybe the real story happened offscreen, just like the Duffers said (but I'm hoping to see it onscreen too).










