"We're a work in progress," said defensive coordinator Dom Capers.

Miami is 0-4 and has given up 103 points, the highest total it has allowed in the first four games of a season since 1989. Overall, the Dolphins are ranked 21st.

"I think it's a great example of how fast things can change in this league," Capers said.

Now in his 22nd season in the NFL and his second in Miami, Capers, a former University of Hawaii assistant, helped build a respected defense in Miami last year, and at previous stops, including a stint as head coach of the Houston Texans, whom the Dolphins face Sunday.

"Dom has proven over a length of time that he knows what he's doing," said Jason Taylor, the 2006 NFL defensive player of the year. "It takes more than just coaching to make this thing work. It takes players, too. Right now the players aren't doing a very good job and I'm sure Dom would say he was doing some things wrong, because everyone looked at it that way."

Part of the problem has been Miami's run defense, which ranked eighth in the league last year and now ranks last.

"If you don't stop the run in this league, then it becomes hard to do a lot of things that you'd like to do," Capers said.

Capers said offseason departures and injuries hurt Miami, but he looks for improvement from younger players.

"The worst mistake you can make is take a system and say 'This is our system,"' Capers said. "And you've got to adapt the system to the players. And that changes from week to week. That's the challenge that we have in this league."

Safety Yeremiah Bell injured his Achilles' tendon in the season opener and a concussion has sidelined middle linebacker Zach Thomas for two consecutive games.

Defensive tackle Vonnie Holliday and linebacker Channing Crowder left Sunday's game in the first half because of ankle injuries.

"Dom and I are always communicating," coach Cam Cameron said. "You are always communicating on who's active, who's going to play, what's plan B, what's plan C. We have gotten to almost plan D in some cases, especially when Channing went down."

Cameron said Holliday will need a week to two to recover from a slight fracture. Thomas, Taylor, Crowder and reserve safety Donovin Darius were all limited for practice yesterday.

The team announced Wednesday that safety Travares Tillman has had arthroscopic surgery on his left knee. Cameron said Tillman will miss Sunday's game.