Second year quarterback Dan Marino's passing ability became the focal point of Miami's offense and in 1984 he exploded to set league records with 5,084 passing yards and 48 touchdowns. Marino's touchdown record was broken by Peyton Manningtwenty years later and the yardage record was broken by Drew Breestwenty-seven years later. The Dolphins attempted early on to make a run at a perfect seasontwelve years after pulling off the feat, as they won their first eleven games but were upended in overtime by the San Diego Chargers. The Dolphins scored more than 500 points for the first and to date only time in their history,[b] as they scored 513 points and finished 14–2, their best record since the undefeated season.
The year began on a somber note, as running back David Overstreet was killed in a traffic collision in June. The Dolphins wore helmet decals with the number 20 (his jersey number) in his memory during this season.
Dan Marino had one of the best passing days of his career, completing 21 of 28 passes for 311 yards with 5 TDs and no interceptions for a Passer Rating of 150.4. This game also marked the emergence of Jim "Crash" Jensen, who lined up as a receiver for the first time and caught 2 of Marino's TD passes. Until 2015, this was the Dolphins' last road win over the Redskins.
Dan Marino increased his two-game total of seven touchdown passes as he tossed a pair of scoring strikes to Mark Clayton within a 1:36 span in the third quarter to lead Miami to its 17th straight victory against the Patriots at The Orange Bowl. Miami intercepted four Steve Grogan passes. Mike Kozlowski returned one 26 yards, then laterred to William Judson who rambled the remaining 60 yards for a touchdown.
A year after being upended in the playoffs by the Seattle Seahawks the Dolphins routed Seattle 31–10. Dan Marino threw for 264 yards and three touchdowns despite being intercepted twice by Seahawks defensive back John Harris. The Dolphins rushed for 143 yards and a Tony Nathan rushing score as well.
In a shootout, quarterback Dan Marino led the Dolphins to a victory by throwing for 421 yards and four touchdowns with one interception. Steelers quarterback Mark Malone recorded 312 yards and 3 touchdowns, but was intercepted three times.