In the aftermath of Matt Birk undergoing arthroscopic surgery on his left knee and free agent Casey Rabach failing his physical, the Ravens have turned to a center with a familiar last name.

Bryan Mattison, the son of former defensive coordinator Greg Mattison, has been lining up at center with the first-team offense. Mattison, a converted defensive tackle from the University of Iowa, said he's slowly developing a groove at his new position.

"I don't know if you're ever comfortable playing center," he said. "If there is a comfort level to playing center, then I've got a long way to go. I've got a lot to learn. But, like I said earlier, with our coaches and our guys on the line, hopefully, I can learn it pretty quick."

Playing center is not an entirely unfamiliar assignment for Mattison, who filled that role on the scout team last season.

"I played it on scout team when I was on the practice squad," he said. "So I was going against [two-time Pro Bowl defensive tackle] Haloti [Ngata] every day and [12-time Pro Bowl inside linebacker] Ray [Lewis] and Sizz [four-time Pro Bowl outside linebacker Terrell Suggs] and Double-J [outside linebacker Jarret Johnson]."

Mattison's brief tenure with the first-team offense has been decent, but he did incur the wrath of offensive line coach Andy Moeller when a botched exchange with quarterback Joe Flacco led to a fumble on Thursday.

Mattison said he had no objection to the team's decision to move him from guard to center.

"They just tell me where to play, and I play it," he said. "I've got a long way to go to learn center. But I've got great coaches here, great players on the team who help me learn. So that makes it a little easier for me."

Dickson to miss preseason opener

Offensive coordinator Cam Cameron said tight end Ed Dickson pulled his hamstring last week and will likely Thursday night's opener at the Philadelphia Eagles. Cameron said he hopes to get Dickson back for two or three preseason games.

"We'll get him back whenever we get him back," Cameron said. "Hamstrings can be a little bit tricky."

In a related move, the team added tight ends Jonathan Stupar and Kris Wilson. Stupar spent three seasons with the Buffalo Bills, setting career highs in catches (12) and yards (111) in 2010. Wilson was an H-back for the San Diego Chargers for the past three years, catching six passes for 73 yards last season.

Stupar wore No. 86, which was Todd Heap's number for 10 seasons.

To make room for them, the club waived rookie safeties Eugene Clifford and Michael Ricks.

Kindle gets green light for opener

Defensive coordinator Chuck Pagano said outside linebacker Sergio Kindle will make his debut against the Eagles, and first-round draft pick Jimmy Smith also might see action even though the cornerback has been hampered by a groin injury for the past week.

"We're being pretty cautious with him still," Pagano said of Smith, who missed four straight practices before he participated briefly in workouts on Saturday and Monday. "He jumped in there [Monday] and did a little bit of special teams, and he got a few reps here and there. But we're making sure we don't push him too hard and he has another setback."

Kindle, who missed the 2010 season after fracturing his skull in a fall, will play in the Ravens' sub defense and in pass-rush situations.

"We want to get him out there, put him on the edge and let him go," Pagano said.

Pollard off to good start

Since signing with the Ravens last week, strong safety Bernard Pollard has made a good first impression on the team. But he is rankled by the talk that he has deficiencies in the back end.

"The type of player that I am, I'm a hard-nosed player, and I believe with any player in the NFL, [if] you put him in the right position, they're going to make things happen," Pollard said. "And every player is put in the right position [with the Ravens], whether it's offensively or defensively or special teams. I think the coaching staff here does a great job with that, and I'm excited."

Pollard, who had five sacks, seven interceptions (one returned for a touchdown) and eight forced fumbles in 76 career games with the Kansas City Chiefs and Houston Texans, has definitely caught the eye of his teammates. Commenting on the team's depth at safety, cornerback Chris Carr said of Pollard, "He's looked phenomenal these first couple days."

End zone

Free-agent wide receiver Jerricho Cotchery is scheduled to visit the Ravens on Tuesday. ... Cornerbacks Domonique Foxworth and Carr and defensive end Cory Redding did not practice Monday. Both Carr and Redding were present from the start of practice, and Foxworth walked out to watch midway through the session. The reasons for their non-participation were not disclosed. … Birk (left knee), wide receiver James Hardy (hamstring) and running Matt Lawrence (unspecified) also did not practice. … Long snapper Morgan Cox was removed from the physically-unable-to-perform list, and he practiced for the first time on Monday. Cox had missed the first six days of training camp while the NFL and its players finalized the new 10-year collective bargaining agreement and then the past three days while recovering from surgery to repair a torn anterior cruciate ligament in his left knee. … Rookie wide receiver Rodney Bradley (unspecified) also returned to practice.

edward.lee@baltsun.com

Baltimore Sun reporters Ken Murray and Jamison Hensley contributed to this article.