The fluidity with which Martinelli and Trossard (Jesus earlier in the season) interchange positions, leaves the opposition defense in complete chaos on how to mark that space. It not only liberates Martinelli and gets him closer to the goal, but also creates more space for Xhaka to run into and you can instantly see he is more effective with Trossard up front than he was when Eddie played there.
I think this is the blue print of how Arteta wants the system to work. Total control in possession playing high risk combinations while also controlling moments in defensive transitions with Partey-Gabriel-Saliba behind the ball.
