The Boston Celtics traded Jrue Holiday and Kristaps Porzingis. Why did they do that? What could be next? Here's an explainer.

The Celtics received guard Anfernee Simons in the Holiday trade and forward Georges Niang in the Porzingis deal, plus a total of three second-round draft picks.

The Celtics shipped the 35-year-old Holiday to the Portland Trail Blazers for the much-younger Anfernee Simons, and Holiday wasn't a fan of the move. Per Heavy Sports' Steve Bulpett, one source said Holiday is "pissed" about being traded to Portland.