Nolan Arenado and his go-go inner motor are running healthy, happy and tiptop at third base for the Rockies. But the all-star Gold Glover needed a brain break. “Nolan is a perfectionist. He’s hard on himself,” Rockies manager Walt Weiss said. “That can be mentally and emotionally draining.” So on Monday, Weiss plopped Arenado on the bench.