Football seasons are built on hope and investment, and the New England Patriots entered theirs with a marquee acquisition meant to signal a new offensive era. But in Seattle, on the first night of the season, both the game and the health of star receiver A.J. Brown slipped away before halftime — leaving the franchise with a loss in the standings and an unanswered question at its most important skill position. It is a reminder that in football, as in most human endeavors, the distance between ambition and outcome is measured in moments no one can predict.