Ferguson was the team's only pure and dominant two-technique player, a guy who demanded and absorbed double teams with regularity. Reserve Paul Soliai, recovering from a bad ankle, is having a solid season but is still learning the two-gap game; he's a better one-technique lineman right now. Ditto Randy Starks, though he is adept at playing over (or off) any of the offensive line positions. Reserve Tony McDaniel is a good rotation player, but isn't dominant enough to line up on the nose full time.
In some ways, this is the nightmare scenario for defensive coordinator Paul Pasqualoni. In the 3-4 defense, Ferguson was the one guy that was irreplaceable. His presence created flexibility all across the defensive front. Without Ferguson, the options available to Pasqualoni are fewer.
Part of the answer to the problem could be a shift towards more 4-3 base and variant looks. The Dolphins have the depth to play that defense and play it well, with Starks and Soliai manning the tackle spots, and Kendall Langford and Jason Taylor lining up at DE. Starks, McDaniel, Matt Roth, and Phillip Merling would give them a solid rotation. At LB, Channing Crowder has played the Mike position many times in the past. Cameron Wake and Joey Porter would be the logical choices at the Sam and Will positions. Akin Ayodele, Reggie Torbor, and Charlie Anderson would be the top reserves.