NAPA — It wasn’t a great day for a high-priced cornerback as the Raiders training camp rolled on with Day 6 of practice.

Here are three things we learned:

1. Sean Smith could be in trouble: The Raiders guaranteed Smith $20 million when they lured him in free agency last off-season away from the AFC West rival Kansas City Chiefs on a four-year, $38 million deal.

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NFL Week 2 picks: 49ers, Raiders come away winners His debut game was awful (he was benched in the third quarter after allowing a 98-yard touchdown pass to then-New Orleans Saints speedster Brandin Cooks) and overall his production over the 15 games he played didn’t match his paycheck.

A week into camp and Smith seems to be in real danger of losing his starting job — and this is with first-round pick Gareon Conley still not healthy enough to practice. On Friday, Smith was relegated to working with the second-team defense. TJ Carrie replaced him with the starters. Even in the nickel package with three corners, it was undrafted rookie Breon Borders who slid in there as at the slot position. For complete Oakland Raiders coverage follow us on Flipboard.

This could just be a chance to deliver a wake-up call to Smith, but it wasn’t a good sign when on the first play of one of the full-team sessions with that second string that he lost track of Johnny Holton to give up a big pass play. A similar thing happened on Thursday when defending Michael Crabtree while working with the starters. Smith looked frustrated both times.

The pressure is on Smith this year. He’s making $9.5 million, including a recently-earned roster bonus, but carries no guaranteed money in 2018 so the Raiders could cut him and not owe a penny.

It was long expected that Conley would immediately step into at least the starting slot role when healthy and available, but he may have a chance to be one of the starters on the outside (and perhaps slide inside for nickel packages) if he recovers quickly from the shin splits.

Carrie is obviously getting his looks, although his biggest highlight Friday was getting in a brief altercation with Crabtree. But Dexter McDonald had another nice day of practice that included three pass breakups on balls thrown to Cordarrelle Patterson. And Borders getting his shot with the 1s shows how much he is impressing the coaches — and Derek Carr.

“Every time I turn the film on it’s like he makes a play,” Carr said of Borders. “That’s how those guys catch your eye. When you’re an undrafted guy, it’s hard, because obviously you’re not going to have the first or second-team reps all the time, obvviously. It turns into, `Who’s 31?’ kind of a thing. And then throughout the off-season, here at camp, he’s really proven himself. The more guys we have like that that can make plays, I’m all for it.”

2. The rise of K.J. Brent: On the topic of under-the-radar guys making an impression, there’s Brent, a former undrafted free agent who spent last year on the practice squad. With Amari Cooper out nursing a left knee injury (Cooper also missed Tuesday’s practice), Brent saw a chunk of plays with the starters.

Brent caught a nice deep pass over the middle from Carr, holding on even after he took a pop from safety Reggie Nelson. On another play, Carr scrambled far to his left before finally finding Brent trailing back to his side of the field for a touchdown. Now, that one probably would’ve been a sack, but Carr praised the way Brent stayed with the action.

“He is a guy, he has to do the dirty work, and he knows that,” Carr said of Brent. “He has to do the dirty work, he’s got to go in there and, hey, ‘If Coop goes down, I got to step in and be the X receiver for an explosive offense.’ As you can see he’s doing a really good job of that.”

Brent said he’s enjoying the competition up here. Like our Oakland Raiders Facebook page for more Raiders news, commentary and conversation.

“This is our job. People are trying to feed their families. Everybody’s trying to get a spot on this team,” Brent said. “It’s always good to be able to compete and make plays against these great guys I’m playing against.”

He’s also not focusing too hard on how the roster spots line up ahead of him in terms of making the roster.

“I’m not worried about the numbers,” he said. “I’m just trying to focus on what I need to do, what I’ve been told I need to do, things I need to work on and be able to execute to have even a chance to make a spot on this team.”

For Brent, he says that’s using his 6-foot-3, 200-pound to his advantage.

“As long as he can continue to make those tough catches,” Carr said. “He’ll tell you he’s not a 4.3 (40-yard dash) guy, he’s got to make those contested grabs and he’s done a great job of that so far.”

3. A healthy dose of Eddie Vanderdoes: The Raiders third-round pick looks like he’s not merely going to be in the mix to start, but could be an impact player. He’s looked big, strong and active while turning heads in his first week working with the veterans.

Carr didn’t mention him by name, but sure seemed to be alluding to Vanderdoes — who had a sack against him in team drills — when talking about the progress the Raiders defense is making.

“The more difficult it is for us on offense, with the kind of weapons that we have and the talent that we have, … it’s just going to help our team,” Carr said. “There was one today, and I went over to Khalil (Mack) and said ‘So-and-so is going to be a good player,’ and he said, `Yeah, I know.’ He was standing right there by us and I was like, ‘It’s good for the Raiders, but I’m not going to tell you yet.’

“It’s one of the younger guys. As him and I see our team grow, and the competition, they’ll get us on a couple, and we come right back and get them on a couple. When it’s that even, those are really good things. Now it leaves the coaches headaches, but as players it shows us we’re going to have a really good football team.”

EXTRA POINTS

— Running back and noted Skittles consumer Marshawn Lynch was greeted by a young fan holding out a pack of the candy as he left the field Friday. Lynch got a running start, snatched the Skittles as he raced by and heading into the locker room, showing his breakaway speed.

— Seventh-round pick Elijah Hood also showed the breakaway speed when he broke through for a 90-yard touchdown run during team drills, the best play of the day.

— Undrafted tight end Pharaoh Brown has had some ball control issues throughout his time with the Raiders and really struggled Friday. He dropped a pass in the end zone that should’ve been an easy touchdown, then added another wide open drop after he got free down the middle of the field later.

— Second-round safety Obi Melifonwu didn’t practice, the first time he’s sat out this camp.

— The Raiders waved defensive end Chris Casher to make room for linebackers IK Enemkpali and Rufus Johnson, both of whom made the practice debuts.