Patrick Peterson wears a black nose and mouth covering at practice every day, doing his part to keep the coronavirus at bay during Cardinals training camp.

It also has the unintended consequence of forcing attention to a specific segment of his face, which coach Kliff Kingsbury notices every time he looks over.

"He's been locked in," Kingsbury said. "He's got the eye of the tiger."

The 30-year-old cornerback's normally-piercing voice has been quieter this year -- like a predator lying in wait -- and it is easy to understand the motivation.

Peterson was not eligible for the Pro Bowl last season because of a six-game suspension, ending his streak of eight straight appearances to begin his career. He was not voted among the NFL's Top 100 players for the first time since his rookie season. There have been whispers that his best days are behind him.

For a player who has long been recognized as one of the league's best cornerbacks, it's a startling about-face in perception, and Peterson believes those fading his effectiveness will soon see the error in their ways.

"I think some people forgot what I bring to the table, what I bring to this team, and what I mean to the cornerback position," Peterson said. "I don't necessarily feel I have anything to prove, but I just want to go out there and play at a high level for 16 weeks and shut the doubters up.

"Some say I may have lost a step, but it feels like I gained a couple. This year is going to be fun. The focus is on another level. The intensity is on a whole other level. I'm ready to play. I can't wait."

Peterson was given a Pro Football Focus grade of 68.6 last season, his lowest since a 2014 campaign in which an early-season Diabetes diagnosis sapped his natural ability.

He bounced back fabulously from that, making the All-Pro team in 2015.

That was in the prime of his career, and it was easy to assume Peterson would be back to normal once healthy. Now Peterson is fighting Father Time, which is why he was a workout demon this offseason in preparation for 2020.

"As you get older, they say some of your skills may diminish," Peterson said. "You may have to work a little bit harder in the offseason to put your body in certain conditions to where it knows how to respond when scenarios pop up in a game – finding a way to dig deep."

When defensive coordinator Vance Joseph arrived last season, he saw vintage Peterson in offseason work and training camp, but the early-season suspension crippled his effectiveness.

"Before he took his vacation, he was Pat P," Joseph said. "When he came back, he wasn't the same player. You ask him and he'll tell you."

After seven inconsistent weeks, Peterson finally found a groove in the final three games. Against the Browns in Week 15, he asked Joseph to let him shadow Odell Beckham, Jr., and did a fantastic job.

If Peterson can play at a Pro Bowl level in 2020, it will help cushion the blow of Robert Alford’s likely-season-ending torn pec. The Cardinals didn't have Alford, their projected No. 2 cornerback, all of last year, either, but were fine down the stretch once Peterson started to perform.

"As he played better, our defense played better," Joseph said.

Kingsbury said Peterson has been "as good as anybody in the league" during training camp, which the Cardinals expect to carry over into the regular season.

Peterson is counting down the days to the Sept. 13 opener against the 49ers, which he believes will be the start of his redemption campaign.

"I'm just extremely focused, extremely dialed in," Peterson said. "I'm ready to play some of the best football I've ever played in my 10-year career."