LAKE FOREST, Ill. -- When organized team activities began for the Chicago Bears on Tuesday, changes on defense went beyond new players fitting into their spots and veteran Shea McClellin moving from defensive end to linebacker.

Cornerback Tim Jennings found himself playing a new spot as well. The two-time Pro Bowl corner moved to nickel-back for passing downs and first-round draft choice Kyle Fuller played the left cornerback position.

"We're going to try it out," Jennings said. "We've got to get Fuller out there, so I'll move in on nickel packages and we'll bring Fuller in at left corner.

"Hopefully, it will be a full-time thing. It's a little different for me. I've got to get back acclimated to playing nickel and playing two positions on defense. Once I get that going, it'll be a good transition for all three of us."

The nickel spot was manned last year for the Bears by rookie Isaiah Frey, who played there because Kelvin Hayden suffered a torn hamstring in preseason. On draft day, the Bears talked a lot about Fuller's experience playing nickel at Virginia Tech, but they want him to learn the regular cornerback spot first before thinking of him as a nickel who matches up on a third wide receiver. So Jennings returns to a spot he really hasn't played since first coming to the Bears in 2010.

"It's a little different," he said. "You're just another linebacker, an athletic linebacker. You have to be able to see a lot more things. You've got to be able to see a lot more backfield sets."

Jennings was more than just doing what coaches asked. He really does like the idea.

"I've been kind of wanting to play nickel since I got here," he said. "So now that I have the opportunity, I'm kind of excited about it. We'll see how it goes."

The 5-foot-8, 186-pound, nine-year veteran also has more run-stopping responsibility. He'll be able to blitz out of the nickel. It's a thought that he finds intriguing because he has no career sacks.

It seems a bit of a risky move considering how effective Jennings had become at his old spot. Only Seattle's Richard Sherman has more interceptions among cornerbacks than Jennings (13) during the past two years.

The nature of the position -- both stopping the run or even guarding slot tight ends -- is that it requires a corner who is more physical. The Bears already have to be wary of cornerback Charles Tillman's physical situation after a torn triceps limited him to half a season. And now their second Pro Bowl corner is left playing a more difficult spot.

The switch leaves questions about whether Hayden has a role with the team this season.

Traditionally a strong third-down percentage defense, the Bears ranked 25th stopping third downs last year, which helps, in part, to explain the desire to convert Jennings.

As for the other big conversion, McClellin played mostly with backups at middle and strong-side linebacker in his first practices since moving from end.

"My first two years weren't the greatest, but I think linebacker is a natural fit for me," said McClellin, who was a college linebacker in a different type of system. "I think it's what I should be doing and I'm very excited about it."

McClellin's footwork appeared very rusty when dropping in the nickel coverage. He had some trouble quickly picking up receivers flaring out of the backfield, and going deep with tight end Martellus Bennett once. Still, for someone who hadn't done this much -- if at all -- he didn't come away discouraged.

"The instincts are there," he said. "I've just got to work on the concepts, the routes."

New Bears defensive end Jared Allen said McClellin's switch isn't unusual in today's NFL schemes.

"You see that so much throughout this league, and the cool part is that he's athletic enough to do it," he said. "I've watched guys go from middle linebacker to fullback.

"It's one of those things: The more you can do in this league, the longer you'll be around. Obviously, they feel he has worth coming back off the edge. For me, if I had to go to linebacker, I'd be cut. That's not happening: I'm a one position type of guy."