Just a guess, but I'm thinking the Rockets want to build around Sengun. They probably want a tough and more consistent backup center for Sengun so they can rest him more. Currently, Boban and Jock Landale don't seem to be able to fill those shoes. Adams was hurt and didn't play at all this season, but he's expected to recover and be able to play starting next season. Adams' stat line prior to getting hurt is a huge upgrade vs Boban/Landale. But with this trade, the Rockets will have a center overload, and will probably make some moves in the off season.

Also, as a tough, hard working veteran center, Adams might be able to teach Sengun a thing or two and be a good role model for the young talented center.