FOR A VARIETY of reasons, the Cardinals were an interesting test case for this Eagles defense, first and foremost because Arizona is the one nondivision team the Eagles have faced in each of the first three years of the Chip Kelly regime.

To the numbers . . .

In 2013, they allowed 350 yards in a 24-21 win. Last year, they allowed 400 yards in a 24-20 loss. On Sunday, lest you need a reminder, they allowed 493 yards in a 40-17 loss.

You don't need graphing paper to know the line is headed in the wrong direction. Kelly was asked the Billy Davis question again yesterday, and his response was the same as it has been all season. He is "very confident" in his defensive coordinator, end of story.

Kelly has never wavered in his support of Davis, and there is no reason to think anything can happen in the last two games of the season to shake that faith. Which leads to a question:

What can change?

Kelly surely understands that something has to give. Say what you will about his decisions to cut DeSean Jackson, trade LeSean McCoy and acquire Sam Bradford, but they are not the moves of a man who believes in the power of the status quo. And when you consider the alarming condition of the depth chart on the offensive side of the football, where the Eagles need to upgrade both guards and at least one wide receiver, it is fairly obvious the current state of affairs on defense will not suffice.

They've allowed 400 yards of total offense in each of their last five games and in six of their last seven.

"We need to find that team that played against New England and played against Buffalo for us to have a chance this week against Washington," Kelly said.

The numbers say the pass defense has improved, but the eyes tell you John Brown should have caught a 70-yard-plus touchdown on the first play of Sunday's loss, and that Carson Palmer was pretty much free to do as he pleased throughout the romp (he seemed quite content to continue handing the ball off to David Johnson, who gained 187 yards on 29 carries).

Against the run, the inside linebackers have been the biggest weakness, but there does not appear to be a whole lot of wiggle room there. If Davis cannot find a way to get more production out of Mychal Kendricks, that contract extension is going to look like a big mistake. Jordan Hicks will be back from a torn pectoral muscle, and it's worth remembering that Kiko Alonso is coming off ACL surgery and was sidelined early this season with a sprain in the same knee.

Against the pass, Byron Maxwell isn't a shutdown corner and was never expected to be when he played in Seattle. The addition of such a player would do wonders for Davis' man-high scheme, but it is hard to believe that the Panthers will allow Josh Norman to walk when he becomes a free agent after the season, and the Eagles' decision to overpay for DeMarco Murray could limit their ability to win that kind of bidding war. (The Rams' Janoris Jenkins is also scheduled to become a free agent). The other way to make the cornerbacks better is to ask less of them. That is, to get to the quarterback quicker. Again, though, the Eagles are locked in to Kendricks and Brandon Graham, and they aren't going to upgrade over Connor Barwin.

Again, what can change?

The fact of the matter is that the Eagles are still feeling the effects from their atrocious 2010-11 drafts, where Graham is the only player remaining of the 12 selections they made in the first four rounds. They took Kendricks and Vinny Curry in the second round in 2012, while Bennie Logan was a find as a third-rounder in 2013. Kendricks and Curry are indicative of the chicken-or-egg question with regard to Davis' scheme. Curry has spent most of the season as a rotational player, while Kendricks has been mostly anonymous. If their current roles are a product of their individual abilities, then add them to the missteps of the end of the Andy Reid administration. The question is, are the Eagles getting the most out of the abilities at their disposal?

Which brings us back to the Cardinals. All four of their starting linebackers have been drafted over the last three years: Markus Golden and Kevin Minter in the second round, Deone Bucannon in the first, and Alex Okafor in the fourth. Nose tackle Rodney Gunter was selected in the fourth round in 2015. Safety Tyrann Mathieu was a third-round pick in 2013.

Somewhere in the process, the Cardinals have been better than the Eagles. Is it the guys drafting the players, the guys coaching them in practice, or the guy calling their plays?

On Twitter: @ByDavidMurphy