N.F.L. teams are rarely patient. Owners and general managers are more apt to replace a struggling coach than to support him. This past off-season, eight teams switched coaches, not including New Orleans, which welcomed the return of Sean Payton after his one-year suspension. A coaching hire typically takes years to evaluate, but through 12 weeks, all eight coaches are either exceeding expectations or providing hope for the future.

Andy Reid may be the worst thing to happen to struggling coaches. In 2012 under Romeo Crennel, the Chiefs appeared to be a talented team but finished 2-14. Even the biggest Kansas City optimists could not have expected the addition of Reid and quarterback Alex Smith to turn the Chiefs into a Super Bowl contender overnight. But Reid has all but locked up the coach of the year award and engineered one of the great turnarounds in league history. If general managers break close calls in favor of replacing their coaches in the off-season, call it the Reid effect.

Chip Kelly, who replaced Reid in Philadelphia, has done a superb job, too. The 2012 Eagles were a 4-12 team that relied on fourth-quarter comebacks to win each of those games. Philadelphia had an inconsistent offense and a terrible defense, which caused ownership to make the splashy hiring of the off-season by bringing in Kelly from Oregon.

The Eagles’ offense has come close to matching the hype that surrounded Kelly’s arrival. Philadelphia is in the top 10 in yards and points per game, and the Eagles are the only team to rank in the top three in both yards per pass attempt and yards per carry. Quarterback Nick Foles has 16 touchdown passes and no interceptions and leads the league in yards per pass attempt, and LeSean McCoy leads the N.F.L. in yards from scrimmage.