After a season away from football, CB Perrish Cox didn’t have high expectations going into his first training camp with the San Francisco 49ers.

For Cox, making the 53-man roster wasn’t a guarantee and even if he did, the team already had three proven corners returning in Carlos Rogers, Tarell Brown and Chris Culliver.

“I looked at it as they basically still have everyone from last year that was playing,” Cox said. “They were a great team last year and from my standpoint, all I really wanted was a chance.”

Consider his low expectations exceeded.

In the 49ers’ 30-22 win at Green Bay on Sunday, Cox was on the field for 76 percent of the defensive snaps as the Packers relied heavily on its dime defense. With the Packers' affinity for using four-WR sets, Cox was on the field for more snaps (55) than All-Pro LB Patrick Willis (48).

“I wasn’t expecting it. I didn’t,” Cox said. “I expected go out there and do whatever I needed to do, whatever chance I had. To be out there that much, I wasn’t expecting that.”

Cox’s debut with the 49ers also was his first playing inside. Before joining the 49ers, he’d never played on the inside as a defensive back. In the dime packages, that’s where defensive coordinator Vic Fangio has him. Rogers also plays on the inside, while Culliver and Brown play more traditional roles as corners on the outside.

The alignment change requires Cox to cover more slot receivers and communicate more with the linebackers and safeties, but he said he’s confident he’s made significant progress learning the position.

“It was pretty different from the start,” Cox said. “I feel good doing it now. I feel like I was doing it forever. It started from scratch, and at first I was a bit nervous. It was my first time ever playing it. My thought process at first was: ‘Don’t mess up.’”

He credited Willis and LB NaVorro Bowman for helping bring him up to speed on the communication process.

Defensive coordinator Vic Fangio said Cox “did a good job,” but there were “things he could have done better.”

Against Detroit on Sunday night, Cox doesn’t figure to see as much playing time because the Lions don’t usually run as many four-WR sets as the Packers.

That’s all good with Cox. He couldn’t be happier.

“Being away (from football) made me love it even more,” he said.

Jacobs, Ginn don't practice, again: RB Brandon Jacobs (knee) and WR Ted Ginn Jr. (ankle) did not participate in practice again Thursday. 

Lions injury report: WR Calvin Johnson was a full participant in practice Thursday after sitting out Wednesday’s practice with a foot injury. S Louis Delmas (knee), CB Bill Bentley (concussion), LB Travis Lewis (quad), DE Lawrence Jackson (calf) and DT Corey Williams (knee) did not practice. CB Chris Houston (ankle) was a partial participant. 

Follow 49ers reporter Kyle Bonagura on Twitter: @CBS49ers and @KyleBonagura.

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