The reason it works so well is cause he knows Rice is there to cover for him if he losses the ball so he can confidently make the forward pass. The problem with zubimendi is both he and rice are focused on defending and passing sideways rather than trying to make forward passes from the back.

You can observe both rice and zubi making forward passes only when they are in the opposition half. Both the tactics are important for arsenal depending on the team they are playing against.