As someone who's been on the buyer side of the market for the past few months, I think it's even worse for their objective: they might be good at forecasting home prices on average conditional on their statistics, but bad at forecasting home prices of the subset that would be willing to sell to Zillow. Every zillow-owned home I've seen, bar none, has had either a bad micro-location (eg: next to a railroad in an otherwise good location), or a bad interior (eg: a smoker home). The same was true for Opendoor, who are in the same business. IE conditional on Sq Footage, location, acreage, etc. they might be incredibly accurate, but they're only able to buy the 50% below that average (and the gap is large because the missing/intangible variables matter a lot).