Nest shuffles are not a new thing to Pokemon GO. We’ve gone through them more than once before. Each time, it seemed Niantic basically shuffled a few Pokemon around. For example, where some nests may have had a high Omanyte spawn rate before the swap, those nests may have their Omanyte rates swapped with something like Dratini. It was a simple 1 – 1 switch. But this time, it seems it’s not so simple.
The word on the street is that this change is drastic and random. There’s no real way to figure out what each nest has morphed into. There seems to be no rhyme or reason to the scheme. Most likely, this change is to help curb cheating or gaming the system. Now, it’s much harder to use apps and online guides to figure out exactly where you need to go for the Pokemon you want. The only real way to figure it out is to get out there and explore, just as Niantic intended.