GLENDALE, Ariz. -- The Patrick Peterson experiment is apparently over.
Before the Arizona Cardinals held their second practice of training camp Sunday, coach Bruce Arians said he won't be using the All-Pro on offense anymore, leaving Peterson to concentrate on defense while returning an occasional punt.
Peterson, who played 35 snaps on offense in 2013, smiled when he was asked about Arians' decision.
"My duties are now done," Peterson said. "I'm completely OK with it."
In May, Arians mentioned that Peterson's days as a punt returner were also numbered.
On Sunday, Peterson said he's been "relieved" as a returner but said he'll continue to practice with the punt returners in case he's needed due to injury. Peterson held true to his word Sunday, fielding punts as practice began.
During Peterson's rookie season in 2011, he returned four punts for touchdowns and was named an All-Pro at the position. His numbers have steadily declined since -- he returned 33 punts in 2013 for a career-low 198 yards -- while his defensive responsibilities increased.
Being able to focus primarily on defense will only help, Peterson said.
"I think it's just going to take my game to another level now because, now, I don't have to focus on the punt returns. I don't have to focus on trying to remember the offensive plays and things of that," he said. "Now, I can hone in on playing defensive back and just being the best player I can be."
Peterson caught six passes for 54 yards last season, rushed four times for 21 yards and completed one pass for 17 yards. His offensive stint was historic. In Week 2 against the Lions last season, Peterson became the first defensive player since at least 1970 to complete and catch a pass in the same game.
With his focus solely on defense, Peterson doesn't want to see his role as the primary defender of a team's No. 1 receiver change.
When asked if he'd be OK with newly acquired Antonio Cromartie being given that assignment, Peterson's answer was: "No comment."
It might be out of his control, however. Arians said who covers the top receiver will be decided on a game-by-game basis. But he plans on mixing coverages to confuse offenses and allowing each of his shutdown corners a chance at an opponent's primary target.
Peterson has gone to the Pro Bowl in all three years he's been in the NFL, but last season was his busiest because he was used in all three phases. His time during the week was spread thin as well.
In addition to preparing to defend the opposing offense's top receiver, Peterson had to study punters and prepare for various types of kicks and coverages, and he also had to learn which offensive plays he'd be part of. Arians said there were times last season that it was tough finding Peterson on the sidelines for an offensive play.
"It wasn't hard but it was just difficult, so now to finally get an opportunity just to play cornerback, it's just going to make my job that much easier," Peterson said.