I think you've got it figured out.
In Urias, the Brewers are acquiring a versatile defender and a potential alternative for underperforming shortstop Orlando Arcia, who is arbitration-eligible for the first time this winter and whose status will be clearer following Monday’s tender deadline. If the Brewers opt to keep Arcia, he would have to compete for the job with Urias, who can also play second and third base. Second is occupied in Milwaukee by hitting star Keston Hiura, but third base is a question mark, with arbitration-eligible Travis Shaw in a situation similar to Arcia's as Monday’s tender deadline approaches.
https://www.mlb.com/news/padres-get-trent-grisham-from-brewers-for-luis-urias