The Dallas Cowboys' defense is going to be good next season -- and it's not because Monte Kiffin is the defensive coordinator.

It's because, at least for now, we can assume the Cowboys' defense will be healthy.

After all, starting inside linebacker Sean Lee missed 10 games. Bruce Carter, the other starting inside linebacker, missed five games. Jay Ratliff, the perennial Pro Bowl nose tackle, missed 11 games. And slot cornerback Orlando Scandrick missed five.

And we're not even discussing DeMarcus Ware, who played the last month of the regular season with essentially one arm because he had a torn labrum.

Get those guys back and put them each in the lineup for 14 games and the Cowboys' defense will be significantly improved.

Kiffin will help.

He didn't forget how to coach pro football during the four years he spent coaching college football with his son, Lane, at Tennessee and Southern Cal. He'll maximize the talent on this scheme and put the players in position to perform.

If we're honest about it, Ryan put his players in position to make plays -- how many missed tackles resulted in big gains -- but injuries forced so many average players into the lineup, they weren't good enough to make them.

Kiffin won't have that handicap.

He also has enough personnel to make the scheme work until reinforcements arrive.

Ratliff can play defensive tackle, and he'll be a playmaker without the constant double-teaming he received at nose guard. Carter is best when he's making plays sideline to sideline, and this defense will give him an opportunity to chase plays down from behind.

Then there's Ware, who's good enough to excel in any and every scheme.

The best thing Kiffin does is bring a credibility Rob Ryan never had. From the time Ryan arrived, we wondered whether he was good defensive coordinator or living off the reputations of his high-profile daddy, Buddy, and twin brother, Rex.

We still don't know the answer.

After all, Ryan has been in charge of just one top-10 defense in eight seasons as a coordinator.

Kiffin has been considered one of the game's best defensive coordinators for more than a decade. He has 26 years of experience, and the players know his scheme works.

It's fundamentally sound and the Cowboys will win with it -- as long as they stay healthy.

In the end, the scheme doesn't matter that much. It's all about the players. If Kiffin's players remain healthy, then his defense will be better than anything Ryan put on display during his two seasons in Dallas.

The Cowboys' defense had one of its worst seasons in team history, allowing a franchise-high 5,687 yards in 2012.

You could blame Rob Ryan's scheme or the loss of five starters and two main defensive contributors to injury for the issues.

You could also blame the emotional toll the defense endured over the death of practice squad linebacker Jerry Brown.

But you can't blame all the problems on Ryan. And surely you can't expect new defensive coordinator Monte Kiffin to fix everything that's wrong with the defense.

It's going to take time.

Derrick Brooks said as much when Kiffin arrived in Tampa Bay in 1996. Brooks, a linebacker for Tampa Bay the year Kiffin took over as defensive coordinator, said the defense had problems during the first half of the season because players needed to adjust to the new scheme.

It's a conservative defense with few blitzes and some zone coverages from the cornerbacks. It's a defense designed for the front four to put pressure on the quarterback and allow the seven other defenders to force turnovers.

The Cowboys' secondary doesn't create enough turnovers. Brandon Carr and Morris Claiborne, the starting cornerbacks, combined for four interceptions. The Cowboys finished tied with Kansas City with an NFL-low seven interceptions in 2012.

Kiffin's scheme can't change that. He can put more players in zone, which is what Ryan did, but it doesn't guarantee more turnovers.

The Cowboys' pass rush doesn't have the youngest players, either. Nose tackle Jay Ratliff -- if he's not cut -- is coming off sports hernia surgery. He turns 32 in August. Jason Hatcher, another expected defensive tackle, will be 31 in July. DeMarcus Ware, the talented outside linebacker, is being moved to defensive end at the tender age of 31. Kenyon Coleman, who started at defensive end before a triceps injury ended his season, is a free agent. He'll be 34 if you bring him back to play the other end spot.

The youngest man in the group is Anthony Spencer, who becomes an unrestricted free agent in March. Spencer, coming off a career-high 11-sack season, turns 29 on Jan. 23.

The NFL is a young man's game. We don't believe Ware is past his prime -- far from it -- but he's coming off shoulder surgery and he's in his 30s. There are no guarantees Spencer will re-sign with the Cowboys, who haven't indicated whether they want to pay $10 million to franchise him again. The men up front will be older, unless the team lets Ratliff go and signs a younger player to pressure the pocket from the middle.

Over time Kiffin's defense will help the Cowboys, but not in the early going. That's going to be a rude wakeup call for some.