Statistically, the Miami Dolphins had one of the 10 worst run defenses in the NFL last season. They yielded 1,937 rushing yards, or 121 yards per game. They also allowed 4.3 yards per rush attempt.
Defense has long been the Dolphins' calling card, but it slipped in a big way in 2014. That's why, despite dramatic improvements on the offensive side of the ball, the Dolphins still managed to finish with the exact same 8-8 record that they had the year before.
That defense will need to return to form in 2015 if the Dolphins are going to deliver on their hopes of finally ending their playoff drought after six years out of the postseason.