OWINGS MILLS, Md. -- There's a reason the Baltimore Ravens defense got shredded by the Oakland Raiders last Sunday -- a lack of energy.

Defensive coordinator Dean Pees didn't hide his anger on Thursday, saying his players didn't have any intensity in allowing the Raiders to score 37 points (Oakland's most in five seasons).

It's difficult to remember the last time a Ravens defensive coordinator challenged his players to play harder. There's a proud tradition with the Ravens' defense of flying to the ball and playing with a relentless style. But on Thursday, Pees referenced the lack of energy eight times in his 8-minute session with reporters.

Missed tackles were a common theme in Baltimore's loss to Oakland. Thearon W. Henderson/Getty Images

"When you don’t play with energy, you end up with six penalties, numerous missed tackles and several big plays," Pees said. "That was the whole bottom line."

A week after shutting down Peyton Manning and the Broncos, the Ravens allowed Raiders second-year quarterback Derek Carr to throw for 351 yards and gave up 5.1 yards per carry. If that wasn’t enough, the Ravens allowed the Raiders to march 80 yards in just 104 seconds for the winning touchdown.

Baltimore now faces a Bengals offense that ranks in the top 10 in both points and yards. How do the Ravens get more energy out of this defense?

"Sometimes we have to take the role as leaders, sometimes as coaches," Pees said. "We’ve got to do some things and just expedite the process a little bit and get them to play harder. Sometimes, it’s changing a little bit of the scheme but it’s not that. If it was changing the scheme, we wouldn’t have played well in the first game. It’s more about within the scheme."

It's telling to hear Pees mention the need for coaches to take the role of leaders. Sunday marked the first time in 17 years that the Ravens didn't have either Ray Lewis, Ed Reed or Terrell Suggs on their defense.

There appeared to be a lack of direction on the field, where the Ravens always seemed to be reacting to the ball instead of attacking it. According to Pro Football Focus, Baltimore finished with 11 missed tackles in Oakland, where C.J. Mosley, Daryl Smith, Kendrick Lewis and Jimmy Smith had two each. It was the most missed tackles by the Ravens since last November, when Baltimore had 12 in a 43-23 loss in Pittsburgh.

Pees isn't the only one who is miffed at the defense. His critical remarks come three days after coach John Harbaugh came down hard on the defensive players.

"I’ll even say we didn’t have the kind of effort we need to have on defense – the kind of all-out, flying-around effort that we expect from a Ravens defense," Harbaugh said Monday. "And our defense played the way we expect them to play the week before, and they didn’t play the way we expect them to play this week. If we’re going to have a chance to be a successful football team, our defense has to step up and play like the Ravens play, and that’s the expectation."

Pees said the lack of effort affected how many times he blitzed Derek Carr.

"I felt like in the last game, because I didn’t feel like we were playing with energy, that’s the worst time to pressure [the quarterback] because that means you’re not going to get there and you’re really not playing aggressive on the back end," Pees said. "I pressured a whole lot less in this last game than I did in the first game. That was not my intent."

The lack of effort didn't come as a surprise, either. According to Pees, there were signs of a letdown throughout the week of practices in San Jose, California. This probably means the Ravens won't be staying on the West Coast between their games at San Francisco and Arizona next month.

"The old saying for years and years and years: You play like you practice," Pees said. "Maybe we didn’t practice as well last week as we should have."

Is Pees worried about where this defense is headed this season?

"One game never defines you good or bad," Pees said. "It didn’t define us after Denver. It won’t define us after Oakland."