Fox is at 61.4TS% & +7 TS+, which is efficient at his volume, but what really lifts the Kings offense is how he improves the shot quality for the rest of the team.
The team gets more transition 3s because the Kings get into the offense so fast with Fox on the floor, and defenses need block the paint to stop Fox from getting to the rim.
In the half court Fox saves the team from dead possessions because he can always get a quality look.
Fox's efficiency is good, but his impact on the team's offense is better than his individual efficiency numbers.
Duncan was a "sneaky athlete" but not in the racist "that white guy can actually jump" kind of way, but in a ""he only moves as fast or jumps as high as he needs to in the moment" so he would randomly turn up his speed and surprise the opponent by being just a little quicker or jumping a little higher than they expected, allowing him to make a play they may have avoided if they were more accustomed to his actual athleticism.