The NFL salary cap has adjusted from the "high 51" rule used during training camp to the 53-man roster rules. Basically, instead of only taking into account the top 51 salaries a team has during training camp, now, every player on the 53-man active roster, the practice squad, and any reserve lists now count into the salary cap. As happens every year, the additional people being counted toward the salary cap has actually given the Miami Dolphins more cap room.
To explain this counter-intuitive phenomenon, you have to look at who counts toward the cap number now. Higher priced veterans are removed when they are cut, meaning someone whose salary is below the "high 51" salaries a team has during camp is replacing that veteran's salary on the roster. Then, players who may have counted toward the cap in camp are now being placed on the practice squad, where their salary is lower than it was as a roster player.
Add in the rookie wage scale, and the 53-man salary cap actually provides space for most teams to still be able to make roster moves.
Then there is roll over money from last year, as well as an ability to borrow money against next year's cap, and teams can find creative ways to still sign a free agent or make a trade, all while staying under the salary cap.
As for the Dolphins, the team currently is 13th in the league with $7.1 million in cap space, according to a Pro Football Talk post yesterday.
The largest cap figure for the Dolphins belongs to left tackle Jake Long, who is a $12.8 million hit this year. Karlos Dansby ($10.7M), Reggie Bush ($6.0M), Kevin Burnett ($5.3M), Randy Starks ($5.0M), and Richie Incognito ($4.8M) make up the rest of the top five salary cap hits this season.
When adding in dead money, or money the team owes to players no longer with the team, two other players bounce up into that top five list, with wide receiver Brandon Marshall still a $5.5M cap hit for the Dolphins, while tackle Vernon Carey has a $4.8M number.
The Dolphins' total salary cap number is a little over $115 million, $106 million in active contracts.
The Philadelphia Eagles currently lead the league in salary cap availability with $21.4M available. The rest of the top five teams are the Jacksonville Jaguars ($20.7), Kansas City Chiefs ($14.5M), Tennessee Titans ($14.1M), and the Buffalo Bills ($13.6M).