NAPA, Calif. (AP) - Raiders quarterback Carson Palmer lofted a tight spiral deep down the right sideline and appeared to have an easy completion to Darrius Heyward-Bey before cornerback DeMarcus Van Dyke came in to break up the pass and knock the receiver to the ground.

A day earlier, Van Dyke spent much of the morning jamming receivers at the line of scrimmage.

It's all part of Van Dyke's plan to become a more physical defender with the Raiders after he struggled at times as a part-time starter during his rookie season.

He still makes some young player mistakes that we've got to get coached out of him, but he continues to make a little bit of progress every day,'' Oakland coach Dennis Allen said Wednesday.He's not where he needs to be yet, but he's got to continue to work, continue to keep getting better and learn the little nuances of the game.''

One of two third-round draft picks a year ago, Van Dyke has been getting plenty of work with Oakland's first-team defense while projected starter Ron Bartell rests his sore hamstring.

Bartell and veteran Shawntae Spencer were signed in the offseason to replace released starting corners Stanford Routt and Chris Johnson after Allen and general manager Reggie McKenzie targeted the secondary for a makeover.

Both are expected to start when the Raiders open the season at home Sept. 10 against San Diego, but Allen and defensive coordinator Jason Tarver are keeping their options open.

That includes Van Dyke, a 6-foot-1, 183-pound cornerback who played in 14 games with four starts as a rookie. He didn't put up big numbers (13 tackles, one interception) and often allowed himself to get pushed out of plays by bigger receivers.

But Oakland's entire pass defense took a beating in 2011. The Raiders were 29th in total defense a year ago, and 27th against the pass.

This year Van Dyke worked out with receivers such as Antonio Brown of Pittsburgh, Chad Johnson from Miami and Cleveland's Greg Little in an attempt to refine his techniques.

He also got a little scolding from his mother when he went home in the offseason.

I went home and my momma told me, `DeMarcus, I'm your No. 1 fan, but you dropped too many interceptions last year,''' Van Dyke said.I'm trying to work on catching the ball and turning my head when the ball is in the air. I did one-on-one workouts with guys. I tried to go up against big receivers, small receivers and the shifty ones.''

Though the Raiders have been in training camp less than a week, Van Dyke has managed to stand out.

In addition to the play he made on Heyward-Bey during Oakland's first practice in full pads, Van Dyke broke up a pair of passes during a team scrimmage drill on Monday and followed it up with another solid workout on Tuesday.

I'm taking everything (the coaches) tell me and putting it on the field,'' Van Dyke said.I'm just going out there and trying to get better at my craft and trying to make plays.''

Much of the attention in Wednesday's practice was focused on tackling techniques, something the Raiders have struggled with for several seasons. Hitting was kept to a minimum and only on a few occasions were players tackled to the ground.

The biggest hits might have been delivered by veteran safety Tyvon Branch and rookie wide receiver Thomas Mayo. The two got into a heated exchange toward the end of the scrimmage drill and both threw punches until being separated.

It's just camp,'' Branch said.The first day of pads, everybody's amped up. Just a little squabble. Nothing major.''

NOTES: WR Denarius Moore (hamstring) was held out of practice, though Allen said it was just a precautionary move. ... Bartell, punter Shane Lechler (knee), lb Aaron Curry (knee) and TE Richard Gordon (hip flexor) were also held out. ... The players have an off day with no practice or meetings Thursday then return on Friday afternoon.