NAPA – The Raiders' defense supposedly is built to let players make plays, and DeMarcus Van Dyke has been trying hard to make a few through the first two games of the preseason. Maybe a little too hard, he thinks.

Van Dyke looked poised to have a breakout camp in early August, when the lanky second-year cornerback made breaking up passes seem a daily occurrence. Since then, Van Dyke has had two very bad days, which happened to occur in the first two exhibition games.

Against the Cardinals last week, Van Dyke allowed two long receptions, missed a tackle on a touchdown run and overall bore little resemblance to the player who impressed coaches and teammates early in camp.

"I've just got to go out there and play ball," Van Dyke said this week. "I'm doing too much thinking, I think, and (defensive coordinator Jason Tarver), he gave me a lot of advice, just telling me to go out there and just play ball. Don't worry about making mistakes, just play like I was the first two weeks of camp."

Van Dyke, the speedy third-round draft pick in 2011 who started four games last season amid injuries in the secondary, arrived in camp this year with 187 pounds on his still-slender 6-foot-1 frame. He had designs on being more physical and making some of the interceptions he felt he left on the field as a rookie.

With Ron Bartell nursing a hamstring injury, Van Dyke joined the first-team defense and shone, seeming right on the heels of Bartell and fellow starter Shawntae Spencer.

The first two exhibition games have tempered those expectations, but today's game against Detroit offers a shot at some redemption. The Lions like to throw, and Van Dyke could find himself lined up across from wide receiver Calvin Johnson, who, as Tarver pointed out this week, is featured on the cover of the latest ESPN The Magazine.

"I would really like to see him play like he plays out here (in practice), and just play with what we know he can do," Tarver said. "And he's heard that from me this week. Play like he plays at practice, because he plays pretty good at practice."

Spencer said he thinks Bartell's return Aug. 6 may have affected the confident way in which Van Dyke was performing at practice.

"He was playing so well when Ron was out with the hamstring, and then Ron came back, and it just felt like everything changed," Spencer said. "He wasn't as aggressive. He was like, 'All right, Ron's the starter,' things like that. I told him, 'Wherever you are on the depth chart, always look at yourself as a starter.' "

Spencer did not play particularly well for the first week of camp. But coach Dennis Allen said that since then, Spencer has been "steady," which is what he expects from a veteran. As a younger player, Spencer said, it can be difficult to weather those down stretches.

"You're going to miss some plays, but you've got to be strong enough to always compete to the max, stay confident and stay aggressive," Spencer said. "If the opposing team sees (your) head hanging, they're coming right back at you."

Van Dyke did his best to sound ready to put the misses behind him.

"You're going to take some bad; you're going to take some good," he said. "It's how you bounce back from it.

"I'm not satisfied with how I've been playing. I haven't been playing like I thought I was supposed to be. But it's a process; it's game by game, preseason games. So hopefully this game, I'll come out and play good."

© Copyright The Sacramento Bee. All rights reserved.

• Read more articles by Matt Kawahara

Order Reprint