For the Raptors: The team is in desperate need of talented guard play, and De'Aaron Fox provides that. Fox is a talented all-star caliber guard that can score at all three levels and is capable of creating his own shot. He brings a valuable skill set to a Raptors team that hasn't had someone of his caliber in a long time. Whilst De'Aaron Fox struggled in the playoffs for San Antonio this season, he is clearly still an amazing player and has a lot of upside. On the trade away end of things, whilst BI is a talented scorer as well, Fox can replace that. His spot in the starting five can be replaced by CMB, who shined for the Raptors in the playoffs. For the Spurs: It's a simple case of needs. Even disregarding Fox's collapse in the playoffs, Harper was immense in the playoffs, and in conjunction with Castle, they have proven that they are capable of being the starting guards for the Spurs. His contract is costly and so, being able to alleviate the team of it whilst still bringing in valuable assets seems sensible to me. San Antonio lacks quality in its forward core, and needs a forward to stand head and shoulders above the rest, and BI can do that. This trade allows for the Spurs to be a more well-rounded team. They also get a backup guard in Gradey to fill a missing guard spot in the rotation, if anyone even cares about that... But, this is just my opinion. Let me know what you think!