One night after he suffered the third concussion and second in six years, Astros outfielder Justin Maxwell was out of the lineup and completely unavailable Wednesday. Although he arrived at Minute Maid Park with what he termed a “light headache,” he was optimistic about being ready to play again Friday. “It’s a little bit sore here on my (left) brow where I took the brunt of the fall,” said Maxwell, who was expected to be reevaluated by team physicians before Wednesday night’s game. “Other than that I feel OK.” Astros general manager Jeff Luhnow and manager Bo Porter vowed to follow the concussion guidelines MLB and the union established in [...]