The Philadelphia Eagles were the dominant team in the NFC for the first three months of the season. But once the calendar turned to December, the defending NFC champions have not resembled the organization that went 9-1 through the first 10 games of the years.

Since that time, the Eagles have lost 4 of their last 5 games, and they have gone from the No. 1 seed in the NFC playoff structure to the No. 5 seed.

The last of those losses may be the most inexplicable. Philadelphia dropped a 35-31 decision to the lowly Arizona Cardinals at Lincoln Financial Field.

The Eagles had a 21-6 lead at halftime and appeared to be in control and an easy victory was at hand. Instead, the Cardinals came out on a mission as Kyler Murray threw 3 TD passes and James Conner ran for the go-ahead touchdown with 32 seconds left.

As a result of the loss, the Dallas Cowboys are now in charge of the NFC East. If they beat the Washington Commanders in Week 18, they will be the division champions. The only way the Eagles can win the division at this point is if the Cowboys lose at Washington and the Eagles win the season finale against the New York Giants at MetLife Stadium.

While there were many Eagles to blame for the devastating loss, head coach Nick Sirianni and current defensive boss Matt Patricia may have done more to let the team down than any of the players.

Nick Sirianni played it conservative on Eagles final drive

After the Cardinals had tied the game at 28-28 on Murray's third touchdown of the second half, the visitors tried to surprise the Eagles with an onside kick. The Eagles recovered the attempt with 5:26 remaining, and clearly had an advantage since they had the ball at the Arizona 45.

Sirianni did not seem to have a go-for-the-throat mentality on the ensuing possession. Instead of trying to attack through the air and put the ball in the end zone, the Eagles threw the ball twice and ran it four times. They settled for a 43-yard field goal from Jake Elliott.

The Cardinals were emboldened after that, as they negotiated 70 yards in 7 plays that culminated with Conner's game-winning 2-yard touchdown run.

Sirianni explained that the Cardinals had given the Eagles gaps to exploit with the run, but they did not hit big plays.

“We could have thrown it there, too,” Sirianni said. “We chose to go there. Hey, it didn’t hit. But I think that sometimes with the gap scheme stuff that you do, it’s more of, you’ve got to do some different things to cancel out gaps if they are bringing everything out.”

Sirianni also admitted that the Eagles should have had timeouts late in the game, but they had been used up as a result of miscommunication. He said that communication issues are on his shoulders.

Matt Patricia's defensive scheme failed miserably

The Arizona Cardinals scored 29 points in the second half against the Eagles. That is completely unacceptable, and Patricia has to take his share of the blame.

Patricia was promoted to defensive play caller late in the season, taking the place of defensive coordinator Sean Desai.

Kyler Murray dominated the game in the final 30 minutes. During the game, he completed 25 of 31 passes for 232 yards with 3 touchdowns and 1 interceptions. Murray also ran 5 times for 24 yards.

In addition to Murray, the Cardinals got a huge performance from wide receiver Greg Dortch. Murray targeted Dortch 8 times and he caught 8 passes for 82 yards. It would be one thing if it was Deebo Samuel of the 49ers or CeeDee Lamb of the Cowboys were making big plays against the Philadelphia defense, but Dortch is not an NFL star. He is an ordinary player who had 22 receptions for 266 yards and 2 touchdowns prior to this game.

Additionally, Conner overpowered the Philadelphia defense with 128 yards on 26 carries. Conner is a tough power back, but he should not be to punish the Eagles in that manner.

The other point is that the defense was unable to stand up for itself on the final drive by the Cardinals. The Eagles are a mature, experienced team that knows how to handle end-of-game situations. Patricia is supposed to help this unit play its best football when the game is on the line.

He has not come close to doing that.

Eagles turnaround seems unlikely at this point

It's one thing for a team to lose one or two late-season games, but the Eagles are in a deep slump with four losses in the month of December. The division is almost certainly the domain of the Cowboys, and the Eagles will have to make a playoff run as a Wild Card team.

Sirianni had this team going in the right direction for the majority of the last 2 seasons. If he can't find that formula again shortly, this year's postseason will be short and painful.