"Just when we think we have things figured out, Jupiter reminds us how much we still have to learn," Scott Bolton, Juno principal investigator at the Southwest Research Institute, said in the NASA statement. "Juno's surprise discovery that the atmosphere was not well mixed even well below the cloud tops is a puzzle that we are still trying to figure out. No one would have guessed that water might be so variable across the planet."
My observation. The report suggests that current planetary accretion disk model(s), contain holes in the origin answers for the solar system and Jupiter appears to be a good example. Exoplanet studies, reviewed carefully shows this too, e.g. hot jupiters, super-earths buzzing close to their host stars, etc. The issue of mixing in Jupiter's atmosphere could also be related to the time scale used, a shorter time of mixing perhaps than long age.