BOURBONNAIS -- Second-round pick Jonathan Bostic is presently the starter at middle linebacker because of the calf injury to D.J. Williams, and first-rounder Kyle Long has taken first-team reps at right guard.
But both rookies also play on special teams.
"They've done well," said special-teams coordinator Joe DeCamillis. "Both of those guys, they've bought in. Florida has done a great job, and Oregon for that matter, of bringing guys in the league that have already played them.
"(Florida) coach (Will) Muschamp does a good job of getting guys to buy in down there, so it was pretty easy with Jon. And Kyle, I think his old man (Hall of Famer Howie Long) probably makes sure that he's going to do things the right way for sure. Both of them have been great so far."
DeCamillis said no determination has been made yet on how many, if any, kicks Devin Hester will return in Friday's preseason opener at Carolina.
Defensive end Julius Peppers (hamstring), linebacker D.J. Williams (calf), wide receiver Earl Bennett (head) and cornerback Kelvin Hayden (hamstring) did not practice Monday, and defensive tackle Stephen Paea was limited (hip tightness).
Defensive end Corey Wootton (hip) returned to full strength, and offensive tackle Jermon Bushrod (calf) was back on a limited basis. Bushrod said he would like to play in the preseason opener Friday night, but the team will err on the side of caution in determining his return.
"I don't think it's out of the realm that he would play on Friday night, but he would have to be 100 percent for us to even think about playing him," coach Marc Trestman said.
"There is no need to push this. We're going to be very patient. Doctors will tell us the condition he is in. We'll evaluate on Thursday and Friday morning and see where we're at."
Just as in the Lovie Smith era, there are expected to be players who make the final 53-man roster primarily, if not solely, because of their value on special teams.
Friday's preseason opener will be as important to them as anyone on offense or defense.
"That's why you have to respect it," said special-teams coordinator Joe DeCamillis. "You have to put them in positions where they're going to do their best and we can watch them on film and evaluate them."
Despite spending the previous five years coaching the Montreal Alouettes in the Canadian Football League, Bears coach Marc Trestman is well aware of Charles Tillman's expertise at forcing fumbles.
"It's like nothing I've ever seen," Trestman said. "His ability to create a turnover is unique. You've got every defensive coach in America watching how he does it, trying to figure out how he can get the ball out the way he does on such a consistent level."
Tillman's 33 career forced fumbles are more than anyone in the NFL since he entered the league in 2003. He had an NFL-best 10 forced fumbles last season.