Under the Ravens' recovery time table, Flynn would likely be unavailable until, at the absolute earliest, Oct. 4 against the Kansas City Chiefs or, perhaps, after the bye week Oct. 24 against the Buffalo Bills.
"I was in the middle of practice and said, ‘Where's Flynn?,' and they said they were taking him to the doctor," offensive line coach Jim Colletto said. "I don't even know what happened. Some of this stuff happens so fast it catches you asleep, so to speak."
Depth is now thin along the interior line behind Rabach, who will play alongside left guard Edwin Mulitalo and right guard Bennie Anderson. Undrafted rookie Lenny Vandermade from USC is the only other center in camp, although Damion Cook has taken some snaps in practice.
Offensive coordinator Matt Cavanaugh referred to Rabach as a "a safety net," because of the playing time he has received since being drafted in the third round out of Wisconsin in 2001. "Flynn's a solid guy who has been the heart and soul of that offensive line for the last five years," Cavanaugh said. "As football goes, you have to be ready to have someone step in. Casey will step in and do a good job."
Rabach sprained his medial collateral ligament last week and missed a scheduled start Friday night against the Philadelphia Eagles. Recovered enough from the injury that he's practicing again, Rabach finds himself a starter by default, albeit not at the position he originally intended.
"Mike's been great, he's a really good friend," said Rabach, a consensus college All-American selection who made the All-Big Ten Conference team at center and guard. "It's sad to see, but I guess that's the game of football. It's a rough sport.
"Hopefully he has a speedy recovery and gets back, and I'll do my best while he's gone."
Rabach started two games last season, participating in 14. He has played in 26 games, starting seven. He's primarily known for his agility and ability to block linebackers downfield at 6-foot-4 and 301 pounds.
Rabach injured his knee in a goal-line practice drill August 14, but said it hasn't given him any trouble recently.
"I feel good, I'm pretty much a 100 percent right now," said Rabach, who has been wearing a protective knee brace. "Obviously I've got it nice and wrapped up and everything just to protect it for right now, but I feel great." Colletto said he's not worried about Rabach's ability to step in for Flynn.
"Casey can play center at the drop of a hat, so there's no problem doing that," Colletto said. "He practiced the last few days and he looked good today. He's fine. He didn't have a serious enough knee injury that he wasn't going to recover from it. With what he did today, you could say he's fully recovered."
Both Rabach and Colletto said they were not sure when Flynn was injured, nor were they immediately aware of its severity.
Rabach said he's confident he can contribute to a line that paved the way for Pro Bowl running back Jamal Lewis' league-high 2,066 rushing yards last season. One of Rabach's two starts last year included the Ravens' 35-0 win over the Cleveland Browns when Lewis ran for 205 yards. "For three or four years now that's kind of been my role," Rabach said of his versatility. "When I get my chance I've got to shine. So I've got my chance now."
Aaron Wilson writes for the Carroll County Times.