Cardinals safeties Antoine Bethea (left) and Tyvon Branch at practice on Thursday.

LONDON, England – Antoine Bethea understood the unease.

The Cardinals signed the veteran safety in free agency this offseason, but most fans of the team weren't excited about that. Instead, they were worried about the players at the position who departed.

After excellent seasons, Tony Jefferson and D.J. Swearinger cashed in on the open market, signing with Baltimore and Washington, respectively. For the first time in several years, it looked as if the Cardinals had a hole at safety.

"As fans, they should have been concerned," Bethea said. "Two safeties that played good ball for their team. What are we going to do now?"

Six games into the season, those fears have been assuaged. Bethea has stepped in seamlessly, with 20 tackles and a team-high three interceptions as the center field rover. Tyvon Branch has picked up the slack at strong safety with a team-high 49 tackles, three tackles for loss and forced fumble.

Branch (third) and Bethea (ninth) have graded out as two of the best safeties in the NFL by Pro Football Focus, doing so at the ages of 30 and 33.

"It's funny," Bethea said. "We were talking when I first came. At one point we were like always the top two in the league in tackles. I knew I had some good football left in me. And obviously Tyvon is showing the same thing, that he still has some good football left in him."

The Cardinals' safety position has seen a lot of players come and go, but it has always been one of the team's biggest strengths. Tyrann Mathieu has been the constant since coach Bruce Arians arrived, while Yeremiah Bell, Rashad Johnson, Jefferson, Swearinger, Bethea and Branch have all made impact plays at the position.

"I think the system works well, especially for safeties," Mathieu said. "It puts a lot of pressure on the cornerback position, but at the safety position, I think guys are able to flourish. I think for most of those guys it's about playing their natural position. I remember Tony's first couple of years, he was the free safety. Once he went down and played strong safety, it got him paid. I think Branch is back at his natural position. He's just comfortable playing tight ends and playing in the box."

Mathieu's point about the cornerbacks is well-founded. There are many times when the safety help is minimal, especially on the side patrolled by star cover man Patrick Peterson. That allows Bethea to lurk.

"In my mind I'm thinking, 'They're not really going to throw to Pat's side,'" Bethea said. "If they do, he can kind of handle his own. I can cut a half or a quarter of the field off. And now, it's kind of playing into my hands, playing into my advantage. Having a guy like Pat on the field, it helps me change my mentality. You do want to be a sideline-to-sideline safety but sometimes you don't have to do that."

While the safeties have come in many different sizes, Arians said they have all fit the scheme. He also gave credit to Nick Rapone for doing a fantastic job coaching the group. And as long as the natural talent is there, the statistics have generally followed.

"If you're playing safety, you better be able to tackle, and we blitz our safeties a lot, so they should be able to make splash plays," Arians said.

After Swearinger and Jefferson left, General Manager Steve Keim used his second-round pick on a contingency plan. Safety Budda Baker has flashed his ability and figures to be a large part of the Cardinals' future, but for now, Bethea and Branch have the position locked down.

"We're doing alright right now," Bethea said with a smile. "Hopefully we continue to play at a high level."