There were many new faces to the Kansas City Chiefs defense in 2014, and after a litany of key injuries shocked this team early in the season, the defensive coaches had to adjust their game plan as they moved forward.

And this proved to be the foundation of a season full of elite defensive performances, both collectively and individually.

The loss of one of the best linebackers in franchise history, Derrick Johnson, combined with the loss of Mike DeVito, the veteran anchor along the defensive line, made for a tough change of plans after both players were lost for the season with Achilles injuries suffered in Week 1 against Tennessee.

Before the season began, Johnson's partner at inside linebacker was slated to be veteran Joe Mays at the "Mike" linebacker position, but Mays was lost for the first eight games of the season after a wrist injury in the preseason.

All three of these injuries to front-seven defensive players made the challenge of putting together a high-performing group much more difficult for the coaching staff. But as the season progressed, the defense continued to soar above just "high performing."

Simply put, they were elite.

"I thought the defense did play well this season," Chiefs coach Andy Reid said. "I was proud of the guys and the way they stepped up. I was proud of the coaches and how they worked through the strength of the player, which isn't always an easy thing to do. There are certain things that can be engrained in you that you just won't change. You see that all the time in coaching.

"I thought we maintained flexibility there and tried to work with what the player was best at."

The coaches didn't necessarily run a cookie-cutter defense and expect the new faces to play with the same strengths and weaknesses as the players they were replacing.

One of those new faces was linebacker Josh Mauga, whose flexibility to play either inside linebacker position in both base and sub defenses made him valuable before the season began as a swing backup.

But after Johnson's injury, Mauga, who had just five total tackles over the past two injury-ridden seasons with the New York Jets, suddenly became a crucial part of the middle of the Chiefs defense.

Mauga finished the season with a team-high 103 tackles.

As a whole, the Chiefs defense was the only in the NFL to never allow 30 points in a game.

They finished second in the NFL in scoring defense with just 281 points given up on the season (17.6 points per game), which is the best for any Chiefs defense since 1997 (232).

In the 51 years the Chiefs have been in Kansas City, they have finished in the top five in scoring defense in 15 different seasons, including the last two with defensive coordinator Bob Sutton at the helm.  This is a franchise that's been built upon the strength of their defenses, and the performance of the 2014 crew wasn't laid upon an easy schedule either.

The Chiefs defense had six games against teams that finished in the top 11 in scoring, and those teams averaged over 27 points per game.

Against the Chiefs in those six games, the teams averaged just 20.3 points per game.

"These guys are a very tight group," general manager John Dorsey said. "I think they play very aggressively. I think that, as a whole, they play the game the way it's supposed to be played. And that's all you can ask for."

While Sutton deserves a lot of credit for having the flexibility to adapt his defense to fit the strengths of the players he quickly had to acclimate to his scheme, Dorsey deserves credit for adding players to the roster for Sutton to work with as well.

The Chiefs had 871 defensive snaps played by players who were brought to this roster after August 20 (the second preseason game). Those players were safety Kurt Coleman (391), cornerback Jamell Fleming (252), defensive lineman Kevin Vickerson (170), safety Kelcie McCray (56) and defensive lineman Nick Williams (2).

"There are some guys that had an opportunity to play that might not have had a chance to play if we had stayed as healthy as one thinks at the beginning of the year," Reid said. "That's a positive going into the offseason."

Reid continued.

"We are a very young football team," Reid said. "In a lot of cases those young guys had an opportunity to grow which will also help us down the road. I think we started the season as the second-youngest team in the National Football League. It's a positive outlook going forward."   

On the season, 76 percent of the defensive snaps for the Chiefs were by players 27 years old or younger. Only 10 percent of the total snaps were by players 30 years old or more, and eight of that 10 percent were by Tamba Hali.

This youth-laden team was challenged this season as well.

"I was pleased that we had the schedule we had," Reid said. "I think we played 11 games against teams that ended up .500 or above and we won nine games. That shows me that we can do some things there as a football team. We just need to be more consistent at it."

It's impossible to talk about the Chiefs overall team defensive performance in 2014 but not discuss the individual performance of Justin Houston, who became the Chiefs' single-season sack leader with 22, breaking Derrick Thomas' franchise record of 20 set back in 1990.

"I'm proud of him for what he did," Reid said. "At no point did you feel like he was going for the record. You felt like everybody around him was pulling for him, but it wasn't from him. He was all about winning and trying to be the leader of the defense. He kept it upbeat and positive for the guys."

Much is made of Houston's ability to bring down opposing quarterbacks, but his ability to be a complete 3-4 outside linebacker has been lauded by this coaching staff throughout the season. How he sets the edge in the running game, his ability to mirror down the line and play the run combined with his willingness to drop into coverage is another reason this defense achieved what it did this season.

Meanwhile, throughout his 20-year NFL career in player personnel, Dorsey said that what the Chiefs defense did this season, as far as overall success and ability to add players and still sustain success, isn't normal.

"It's not," Dorsey said. "What I applaud is, the coaches playing to the strengths of the players and for putting them into position to take advantage.  I thought the defense, week in and week out consistently played at an extremely high level."

They played at that level against quarterbacks the likes of Peyton Manning (twice), Tom Brady, Ben Roethlisberger and Philip Rivers (twice), all of whom finished in the top 10 in passing yards this season.

"Nobody had a 300-yard passing game against them, I think that's an admirable stat," Dorsey said of this defense. "Those [coaches] put them in position to make plays.  I think the coaches deserve a huge amount of credit and I think from the creative side of the game planning I think Bob (Sutton) and his staff deserve a heck of a lot of credit on that."

Besides not allowing a 300-yard passer, the Chiefs defense also never allowed a completion of 50 or more yards, and they are the only team in the NFL that can say either of those things.

Also, the Chiefs defense played its best when it mattered the most, allowing a NFL best of just 51 total points in the fourth quarter all season.

That's just over three points per game on average in the fourth quarter. Simply put. Elite.