Wizards can easily afford a Benn Mathurin extension, giving up that first is worth it because he has an insanely high upside as a 2 way Wing. they also get Bradley who is a veteran big man presence for Sarr.

Pacers do this to avoid a 20+ million dollar extension for Benn Mathurin, Get role players for cheap, and shooters to complement Tyrese. They also get a protected first. Mathurin is nothing what they need, and cheaper players and better fits.