BOURBONNAIS -- Most of the linemen who did the heavy lifting for Rod Marinelli's defense last year are back -- only Tommie Harris is missing.
And there have been some intriguing additions, most notably second-round draft pick Stephen Paea and unrestricted free agent Amobi Okoye.
Blending this new talent with the core group of holdovers is one of the primary goals of training camp.
"Half of our defense have their Ph.D.s in this system," Marinelli said. "Now we've got new guys coming in, just trying to learn it.
"So, as coaches, we've got to make sure our team is ready to play and (at the same time) bring some (new) men on in a short period of time."
If the Bears weren't pumped about the potential of Paea, they wouldn't have chosen him in the second round. But with no off-season this year, he has to accelerate his learning curve.
"The standards are high, and the bar is high," the rookie said. "I have to come in here with that attitude. When you hear 'Bears defense,' everything is about fast, strong, hitting in the mouth and all that, so I have to play up to that."
The 6-foot-1, 300-pounder has the quickness to be a disruptive presence as a 3-technique tackle, and he's strong and stout enough to anchor the line as the nose tackle.
The two positions play side by side on defense, but the duties and techniques that come with each are a world apart.
Paea got all his first-week snaps at the 3 technique, but he also worked at the nose in Thursday night's practice.
Learning both positions well enough to make an impact won't be easy, but his training-camp performance will tell coaches where he will help most.
"I'm going to play him at both," Marinelli said. "You don't like to do too much of that. (Between) a nose or a 3, you only move 12 inches one way or the other, but it's a whole different world.
"I've got to be smart with it. I want to get him in a position where he can be comfortable, and then let his instincts shine."
The 6-foot-2, 292-pound Okoye was the 10th overall pick in the 2007 draft -- as a 19-year-old. But when the Texans switched from a 4-3 defense to a 3-4 in the off-season, his value to that team was diminished.
Not so with the Bears' 4-3.
"He fits, no doubt about that," Marinelli said. "But before I give him expectations, I just want to see what he does well, see how well he understands the concepts of our defense, how hard we're going to play and how fast and physical we're going to play and then we'll kind of go from there."
As with all NFL free agents, Okoye wasn't able to practice until Thursday night, so it will take some time to determine how much of an impact he will make, but he sees himself as a natural 3 technique in the Bears' scheme.
In Harris' seven seasons at the 3 technique, he was voted to three Pro Bowls, but his performance deteriorated a lot in recent seasons and his release in the off-season should provide enough snaps for Paea and Okoye, especially if Paea is asked to give incumbent Anthony Adams some downtime at the nose.
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