This explains everything.
Because rationality and probability have failed to adequately resolve how the Dolphins could be so spectacularly bad for so long, the Miami New Times proffers a theory: it's a curse on Sun Life Stadium, formerly Land Shark Stadium, formerly Dolphin Stadium, formerly Pro Player Stadium, formerly Joe Robbie Stadium, formerly where the Tequesta tribe buried their dead until the Dolphins dug them up in 1985.
The Tequesta inhabited the shores of Biscayne Bay and much of Broward County for thousands of years until the Spanish arrived in the 16th century. They were almost completely wiped out or resettled by the time the British arrived, but left behind plenty of artifacts, including a fruitful site at exactly the spot where the Dolphins' team offices now stand.
According to some archeologists, the spot had been a burial ground for the Tequesta around 800 A.D., and for the Seminole tribe some 1,000 years later.
The Dolphins sought and received permission to carefully dig up the burial ground, as long as archeologists were on hand to examine what the soil turned up.
The Dolphins eventually excavated the burial grounds in six-inch increments, allowing experts to sift through the dirt slowly. Once the area was cleared of artifacts and ancient remains by Dade County archaeologists, the Dolphins were free to continue building the field that their offense would forever explore in six-inch increments.
Did disturbing the remains of vengeful natives cause the decades of futility on the site? One point in favor: the Dolphins went to the Super Bowl four months before digging up the remains, and they haven't been back since. A second point: you saw Poltergeist. Shit's scary.