The groundwork has been laid and the San Francisco 49ers defensive unit is taking heed to Robert Saleh's system. In his first opportunity to speak with the media since the start of training camp, Saleh took to the podium to give updates on five rookies and their adjustments so far at camp.

1. DL Solomon Thomas

Since missing the 49ers offseason program, Thomas has been playing a game of catch-up. While it is still fairly early to assess the third-overall pick, Thomas looked to get a few first-team reps on Wednesday following an ankle injury to defensive lineman DeForest Buckner.

"He's working his butt off," Saleh said. "But, through five days, you know he missed all of OTAs, so he's doing a lot of good things. He looks good, he's working hard, he had a really good play down there moving the ball on the screen, coming off the stack. As he gets comfortable and starts understanding offensive linemen and the things that he needs to do to maintain his gap and his leverage, he's just going to get better." 

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2. LB Reuben Foster**

Foster has dominated third-team reps over the first few days of camp. He's grabbed three interceptions in five practices which has prompted the question, why hasn't he been promoted?

Saleh explained that he will rotate his guys on defense to give each player an equal opportunity during this evaluation period.

"(We're) having rotation with the linebackers to make sure that everyone is getting reps. We have a good group of linebackers. Just making sure that everyone is getting an equal opportunity to be seen exactly the same way. It's not an indictment on who's doing poorly, but it's more of a chance to let those threes get their look at playing against ones."

3. DB Lorenzo Jerome

With the injuries to Jimmie Ward (hamstring), Eric Reid (ankle) and Jaquiski Tartt (ribs), it's far too soon to panic about the safety position. While all three injuries look to be minor, undrafted free agent Jerome has stepped up in their absence and is receiving first-team snaps at free safety. 

"It's a testament to him and the fact he's been able to prepare himself from OTAs to now to give himself that opportunity," Saleh said. "You never want to use that cliché of 'next man up', but he's taking advantage of his opportunity."  4. DL D.J. Jones

The sixth-round pick showed himself well during the team's 1-on-1s and full team drills on Wednesday. early display of strength, athleticism and quickness has earned Saleh's approval through the first five practices of camp.

"DJ's been doing very well. He's showing a lot of the stuff that he showed in college. He's showing that this game is not too big for him," Saleh said "From a strength stand point and effort, he's got those tools, now it's just a matter of understanding how offensive linemen play in this league and the little tricks they have so that way he can do his job better."

5. Ahkello Witherspoon

Third-round pick Witherspoon is in a battle for playing time behind veteran corners Keith Reaser and Dontae Johnson. He received his "welcome" into the NFL by way of a collision at the goal line with Pierre Garçon. In a non-tackling drill, the rookie cornerback didn't properly brace himself for the contact that Hyde was about to deliver. The result wasn't glamorous from Witherspoon's perspective. Even so, Saleh reiterated that he isn't worried his rookie corner.

"I have full faith that Ahkello's going to do exactly what he's been coached to do," Saleh said. "He's not a coward by any means. He will get in there, he will tackle. He's been showing up in run fits, he's physical with his hands at the line of scrimmage. So, we're excited to see what shows up on game day. We think it's going to be pretty cool."