it generally comes to team player health and how they are playing at the end of the season, the eagles last season also had the best record, yet large UNDERDOGS(due to injuries) every playoff game = a touch more motivation for the team, they played GREAT, and one play not going their way in the divisionals = they lose. that = pats win last superbowl not the eagles (since the pats would not have played the eagles)
biggest factor though is injuries- especially to quarterbacks- your team's QB is really good, gets injuried, due to salaries, GENERALLY, the backup is an average QB at BEST- only exception is great qb that is aging and the team drafts a potential replacement that is good, but due to QB being great has no chance at starting- barring an injury or suspension-see Jimmy G in 2016 season-brady suspended 4 games = jimmy g starts games and looks great, but then brady comes back from suspension and ...plays great=jimmy sidelined until getting traded next season to the 49ers, where he....has looked great.
biggest factor though is injuries- especially to quarterbacks- your team's QB is really good, gets injuried, due to salaries, GENERALLY, the backup is an average QB at BEST- only exception is great qb that is aging and the team drafts a potential replacement that is good, but due to QB being great has no chance at starting- barring an injury or suspension-see Jimmy G in 2016 season-brady suspended 4 games = jimmy g starts games and looks great, but then brady comes back from suspension and ...plays great=jimmy sidelined until getting traded next season to the 49ers, where he....has looked great.