SANTA CLARA, Calif. -- In coordinator Robert Saleh's new-look San Francisco 49ers defense, there might be no more important position than free safety. If it isn't the most important position, it's definitely the one that lends itself to the most scrutiny if something goes wrong.

That makes converted cornerback Jimmie Ward one of the most important players in the Niners' locker room. Defensive backs coach Jeff Hafley explained why last week.

"I think everybody has got to be aggressive. I just think, like the rest of them, he’s got to do his job," Hafley said. "Unfortunately, when he doesn’t do his job, all of you guys will notice it a lot more, and everybody in the stadium will see it a lot more. So it might stand out, but it’s all equal. Everybody has their part."

Although no defense can work without everybody doing his job, Saleh's defensive scheme follows a similar blueprint to what the Seattle Seahawks have built under coach Pete Carroll. The 4-3 scheme features a heavy emphasis on playing Cover 3 zone on the back end. That coverage allows the strong safety to play closer to the line of scrimmage, which leaves the free safety alone as the last line of defense responsible for handling the deep middle of the field by himself.

Jimmie Ward has embraced his move to free safety. Thearon W. Henderson/Getty Images

For that scheme to excel, a top-tier free safety -- in Seattle's case, it's potential Hall of Famer Earl Thomas -- who can read quarterbacks, run the alley and make plays all over the secondary is a prerequisite.

"It’s very important," Hafley said. "We call it 'The Eraser' because when bad things happen, he needs to erase it and make sure it’s not really bad. He’s got a lot on his shoulders back there, but he’s more than capable."

If ball carriers break through to that last level, it's imperative to have someone who can bring them down.

"You’ve got to be a great tackler because if the ball busts through, he’s got to be able to get him down," Hafley said. "You have got to be able to run sideline to sideline, and you have to have pretty good instincts. He’s got to be able to see things and go make plays. That’s what the great ones do. We’re gonna let him play ball back there, coach him up, and I think he’s going to be a good one."

Since he entered the league as a first-round pick in the 2014 NFL draft, Ward has almost exclusively played cornerback. He played safety and corner in college at Northern Illinois, but despite persistent questions about moving him to safety, previous regimes have kept Ward at corner. Soon after Saleh and head coach Kyle Shanahan arrived with the new scheme, they decided to move Ward because of the need for someone with more speed and ball-tracking ability to play the position.

With about a week left in the offseason program, Ward's move to free safety has already proven permanent. According to Hafley, Ward hasn't taken reps at any other spot and already has a firm grasp on what he's doing. Further, Ward never offered any trepidation about the position switch.

"He loves it," Hafley said. "I think you can put Jimmie anywhere, and I think he’d embrace it. That’s just the type of kid and person he is. Great attitude, great work ethic. All he wants to do is win. He just wants to go out there and play and make plays. When we talked about it, he was, ‘Coach, whatever you need.’ That’s the type of guys you want on the team."

Although Ward seems to be adapting well to his new/old position, the Niners still have some questions about depth behind him. As it stands, the most likely solution should something happen to Ward would be to move strong safety Eric Reid back to free safety, with Jaquiski Tartt in Reid's place. As for players battling for depth spots behind Ward, undrafted rookie Lorenzo Jerome has a real shot to win the spot, though the Niners have continued to look at alternatives, including a recent workout with veteran Jairus Byrd.

Saleh doesn't seem too concerned about the lack of depth.

“Everything is going good," Saleh said. "The guys are working really hard, depth-chart-wise. You never want to label a depth chart. Everyone is working. Everyone is getting almost equal reps. But as far as the people that are here now, they are doing a very good job, working hard and doing everything they can to get better.”