ANDERSON – Nobody on the Colts expected the change in defensive schemes under new coach Chuck Pagano to come without a few bumps – just not this many this quickly.

Over the past two weeks, Indianapolis’ linebacker corps has taken three big hits.

Backup A.J. Edds, who coaches expected to play a key role this season, tore the anterior cruciate ligament in his left knee during a non-contact drill on the first day of practice. The news Monday was worse: Pat Angerer, the team’s leading tackler last season, will miss at least six weeks after surgery to repair his fractured foot and backup Scott Lutrus is out for the season with a torn ACL.

Newcomers Jerrell Freeman and Moise Fokou are now battling to replace Angerer, Indianapolis’ signal-caller, as the defense changes from a 4-3 alignment to Pagano’s favored 3-4 hybrid look. The next-man-up philosophy is on full display.

“It just has to be done,” said Robert Mathis, the defensive end who is lining up at linebacker this season. “There’s no particular formula that works; we’ve just got to get it done.”

Angerer, a third-year player out of Iowa, had 146 tackles last season after replacing defensive captain Gary Brackett and was expected again to anchor the middle of the new defense.

Defensive coordinator Greg Manusky must figure out what to do and how to get this defense in sync before the Sept. 9 season opener at Chicago, and now he must do it with what amounts to a brand new starting unit.

Mathis and Dwight Freeney, both Pro Bowl ends, are listed as starters at outside linebacker. Kavell Conner, who played outside linebacker the past two seasons, has now moved inside. And Freeman, who spent the past three seasons playing for Saskatchewan in the Canadian Football League, finds himself listed No. 1 on the Colts’ depth chart.

Freeman has an early edge over Fokou in part because he spent the entire offseason with the Colts.

“Pat and I actually worked together a lot,” Freeman said Wednesday. “We talk and if he sees something or I see something, we’ll talk to each other. It’s a pretty good locker room, pretty good teammates in there. We work well together.”

Fokou is a four-year veteran the Colts acquired in a trade with Philadelphia during camp. Fokou started 22 games over the past three years, has 112 career tackles and worked with the starters for much of Tuesday’s afternoon practice.

“Being traded over here, especially with my experience, brings depth to the position,” he said. “I bring a certain level of experience here.”

Numbers are not the problem.

Indianapolis still has 13 healthy linebackers on the roster, including seventh-round draft pick Tim Fugger, who was activated off the physically unable to perform list Saturday.

What the Colts lack is experience.

Freeney, Mathis and former first-round draft pick Jerry Hughes have never played linebacker in the NFL, and Conner is learning a new position. Fokou has played in 43 NFL games. The other eight linebackers have combined for one NFL start and played in a total of six NFL games.

Colts players aren’t fretting, though.

“That’s one of the things about this league that makes it so great, is it’s a brotherhood. When one guy goes down, the next man steps up. And that next man has to treat his job like he’s a starter,” defensive end Cory Redding said. “When he comes in, we shouldn’t miss a beat. He comes in there, he gets all the calls, knows the signals as well. It’s just having that mentality of when one man goes down the next man steps up, regardless of what happens, he gets the job done.”

Note: Redding (left elbow) said he expects to play in Sunday’s game against Pittsburgh.