Posted by ESPN.com's James Walker
A look at the key loss and his replacement for each team in the division:
Who's in: Matt Birk, center
Outlook: Although losing linebacker Bart Scott also was important, the center position could be even more vital because the Ravens play in the AFC North against quality defensive tackles such as Shaun Rogers, Casey Hampton and Domata Peko.
Baltimore is a physical, run-oriented team, and Brown was the top center in the division last year. Brown was very important in the team's three-headed rushing attack. The Ravens will use the same system in 2009 behind Birk, who is a six-time Pro Bowler. But he also is 32 and has some injury concerns.
Who's in: Laveranues Coles, wide receiver
Outlook: The Bengals lost a veteran receiver and got a solid veteran replacement in Coles.
Similar to Houshmandzadeh, Coles should have a lot of opportunities to make plays with No. 1 receiver Chad Ochocinco garnering most of the attention. Although Coles probably won't catch 90 or 100 balls like "Housh" did with the Bengals, 60 or 70 receptions would be a good year for Coles.
Quarterback Carson Palmer has worked hard to develop chemistry with his newest receiver this offseason in hopes that it pays off down the road.
Who's in: Robert Royal, tight end
Outlook: Really, you could pick a number of replacements with the Browns because of the significant turnover of this year's roster. But their biggest trade this offseason involved shipping former Pro Bowl tight end Kellen Winslow Jr. to Tampa Bay.
Cleveland signed former Buffalo Bills tight end Robert Royal, whom coach Eric Mangini was familiar with as the former coach of the New York Jets in the AFC East. Royal is more of a 30-catch tight end than an 80-catch tight end. But Cleveland expects to be a run-heavy team in 2009 so high production from that position isn't a necessity.
Who's in: Lawrence Timmons, inside linebacker
Outlook: Despite his inexperience, Timmons' athleticism and versatility should give Pittsburgh's linebacking group an upgrade, which is a scary thought.
Foote was solid but is primarily a run-stuffer. Timmons is just as physical, but can also blitz the passer and is fast enough to drop deep in coverage and cover tight ends.
Expect defensive coordinator Dick LeBeau to come up with interesting ways to use Timmons this season. Pittsburgh's coaching staff has high hopes for Timmons as a full-time starter.