Chip Kelly said that Bill Davis would return next season for a third year as the Eagles defensive coordinator.

"I thought Billy did a really good job," Kelly said on Monday, a day after the 10-6 Eagles ended the season. "I thought our defense improved in a lot of categories. There's still things we need to clean up."

The first question of Kelly's news conference was about Davis. The Eagles coach, however, made it clear throughout the rest of the session that the team had yet to make final evaluations on the 2014 season.

Despite Kelly's endorsement of Davis, he wouldn't be the first coach to say something definitively one day and change it later on. Former Eagles coach Andy Reid, for instance, said that defensive coordinator Sean McDermott would be back after the 2010 season, only to fire him several days later.

But Kelly has never publicly wavered in support of Davis, whom he hired shortly after being named coach two years ago. The players on defense never wavered, either.

"Billy's called really good games," linebacker DeMeco Ryans said. "He's done a really good job. I think a lot of times things fall on players being in the right position and making the plays we're supposed to make. But I think Billy has done a really good job. I think our defense progressed really well from Year 1 to Year 2."

Statistically, the Eagles were better in some categories, worse in others, but generally status quo. They went from 29th in the NFL in total yards to 28th; 20th in yards per play to 16th; fourth in rushing yards per play to fifth; 20th in passing yards per play to 22d; 17th in points to tied for 22d.

The Eagles made a significant improvement in sacks per pass attempt (from 31st to sixth), but dropped in interception rate (14th to 24th). They improved on third down (24th to 13th), but regressed in the red zone (12th to 23d).

The biggest difference was in "X" plays, in particular 40-plus-yard pass plays. The Eagles allowed the most in the NFL (18), a year after surrendering half that many.

"We were really good in 2013 in X plays. We weren't good at all in 2014 in X plays," Kelly said. "I thought our run defense got better. I thought our transition from coming in here and then playing a wide-nine, 4-3 defense to a 3-4 defense over the last two years - I think Billy's done a really good job."

Davis ran variants of the 3-4 defense at his previous stops as a coordinator with the 49ers and the Cardinals. But he had learned the two-gap 3-4 initially with the Steelers and then when he followed Dom Capers to the Panthers.

The Eagles' 3-4 base package was effective against the run. But the scheme, particularly on passing downs, often left the cornerbacks in man coverage with only a single safety over top. And if the pass rush didn't get pressure, the secondary often didn't have the personnel to stop top passing offenses.

Cornerbacks Bradley Fletcher and Cary Williams would be left alone to cover receivers like the Packers' Jordy Nelson, the Cowboys' Dez Bryant, the Redskins' DeSean Jackson and the New York Giants' Odell Beckham Jr., and the results were often crippling.

"We're a single-high team," safety Malcolm Jenkins said. "We match up, we press a lot. So with that comes one-on-one matchups and you've got to win them. If you double one guy, that means another guy's got a one-on-one he's got to win. We do that so that our pass rush can get home."

Jenkins said he didn't envision many changes in terms of scheme. The Eagles are expected to overhaul the secondary, with Fletcher and Nate Allen likely gone and possibly Williams. They did acquire Jenkins last offseason so that they could stay in their base defense even if offenses rolled out three receivers.

Davis increasingly utilized his dime package with Nolan Carroll as the sixth defensive back, especially after Ryans was lost for the season with an Achilles tendon rupture. In Sunday's season finale against the Giants, with Fletcher sidelined with a hip injury, Davis had Williams shadow Beckham, flexibility he hadn't shown previously.

Kelly and Davis like to minimize the intricacies of their schemes and focus on the importance of execution, but Jenkins said the Eagles defense presented challenges for opposing quarterbacks. But the former Saint said that the scheme's effectiveness was that it wasn't overly complicated for the players.

"It's not as elaborate as, say, a Gregg Williams or Rob Ryan [defense] - where they've got eight-defensive-back packages and crazy things like that," Jenkins said. "To do that you have to have smart players and everybody's got to know their role where the defense is changing every week.

"And that's kind of hard to keep up with as well. So having a defense that doesn't change from Week 1 to Week 16 and you just tweak one thing here and there, it makes all the difference in the world."

@Jeff_McLane