The move is more reflective of Lin's declining popularity since leaving New York, since Nike has the most resources to shell out if they wanted to retain Lin. Given his popularity in the Asian markets in part due to his Taiwanese heritage, it fits with Nike's long-term goals as well. But Adidas has also been active in Asia, with Dwight Howard having put together a strong campaign there in the summers annually.
The move may reflect a growing investment by Adidas into Houston, which has leveraged its brand effectively on a global scale.
Lin is averaging 14.1 points and 4.2 assists per game for the Rockets this season.