1. They appear sticky on the down trend since the prices are dropping faster than their algorithm can assimilate new prices into the system
2. Some data are just plain wrong. I see many sharp upswings and downswings where either they have bad data or the algorithm is choking on non-existing data (like using 0 for input data when data isn’t available)
3. In some cases I have seen it shows sharp upswings but gradual downward slopes, giving an impression that they are eager to increase the zestimates but reluctant to lower them.
I think, on the whole, it is still an immature model.
