The Phillies acquired Jean Segura, Juan Nicasio, and James Pazos from the Mariners in exchange for J.P. Crawford and Carlos Santana this past December.
In my opinion, this acquisition was the best/most important one that the Phillies made this offseason.
This trade set the wheels in motion for the rest of the offseason, making a statement that the Phillies were finished waiting for potential players to develop into stars. They wanted stars now, and saw an open window for sustainable success, with Aaron Nola and Rhys Hoskins to lead the way.