The first heavyweight encounter of the Premier League season was previewed in some quarters as the immovable object versus the irresistible force. Arsenal do not give an inch. Chelsea have been fun and free-scoring under Xabi Alonso. Yet that overlooked something pretty fundamental. The percussive force of Arsenal’s game when they have the ball and want to make something happen. Chelsea landed a significant blow after 77 seconds when Morgan Rogers put them in front with nicely executed volley f…