On most days, Bruce Arena is among the first to arrive at the New England Revolution’s training center, a 68-acre complex carved out of densely wooded wetlands 30 miles south of Boston.

At 70, Arena is at both the apex and the end of his career. The most successful American soccer coach of all time, he has never had a team perform at a higher level than this season. After turning around more organizations than Lee Iacocca, Arena came out of retirement 2½ years ago to take over a floundering franchise that hadn’t had a winning season in four years and guided it this year to the best regular-season record in MLS history.