Perhaps Van Jefferson deserved better than having to enter his rookie season with high expectations. The Rams had traded away Brandin Cooks for the draft pick that became Jefferson, and his age (24) and NFL heritage (father Shawn Jefferson is a highly-respected receivers coach and was once a decent player himself) set a high bar based on the idea that he may not need as much adjustment time as most first-year players.
But there is another, far likelier scenario that could be playing out: Jefferson struggled to handle NFL speed and NFL size during his first season and he would need additional time to adjust to playing with and against professionals.