The researchers didn't explain why the tablet world contracted over the course of the whole year, but its fourth quarter stats offered some clues. Apple was particularly aggressive in updating tablets in 2019, and its lower-cost models were particularly successful -- the 10.2-inch iPad reportedly represented almost 65 percent of Apple's shipments. Amazon has been struggling with a decline in the US, but its budget Fire tablets got a boost through discounts like the Black Friday sale.

For rivals, the problems varied. Samsung fared well with keyboard-friendly tablets like the Galaxy Tab S6, but that wasn't enough to make up for sinking demand for its other slates. Huawei and Lenovo, meanwhile, performed best in their home territory of Asia-Pacific but didn't fare as well elsewhere. The US decision to blacklist Huawei didn't help, either.

The shrinking market leaves at least some these companies in a tough spot, in part because there aren't many clear answers. Samsung may need to either shore up its budget tablet sales or shift even more of its focus to the high end, while the opposite appears to be true for Huawei and Lenovo. And while Apple and Amazon appear to be sitting pretty, they might not have room to be complacent lest their rivals (including Windows tablet and convertible makers) figure out winning strategies.