Posted by ESPN.com's Kevin Seifert
A look at the key loss and his replacement for each team in the division:
Tait Williams Chicago Bears
Who's out: John Tait, right tackle (retired unexpectedly)
Who's in: Chris Williams (2008 first-round draft pick)
Outlook: The Bears originally expected Williams to start at left tackle, and he still projects there in the long term. But the fallout from Tait's unexpected retirement, as well as the free-agent departure of John St. Clair, left Chicago scrambling.
As it turned out, veteran free agent Orlando Pace was the best option. Rather than shifting Pace out of his longtime spot on the left side, the Bears decided to let Williams break into the NFL at what is generally considered a less challenging position.
This seems to be a reasonable arrangement and a good response to Tait's decision. All things equal, new quarterback Jay Cutler would surely prefer backside protection from Pace rather than an untested player. Williams will get a chance to learn the NFL game without that pressure.
Outlook: The Lions didn't lose anyone they had hoped to retain, but the quarterback transition is the biggest item on their agenda this summer.
Culpepper Stafford Stafford ultimately will take over the starting job, but the question is when. Culpepper is viewing this season as a final chance to salvage his career. The pieces are in place for him to have at least short-term success, most notably offensive coordinator Scott Linehan and receiver Calvin Johnson.
Unless Stafford proves to be the rarest of talents, it's likely Culpepper will open the season as the Lions' starter. If he can achieve modest success, he will give Stafford the long-term gift of a full season of development on the bench.
Tauscher Barbre Green Bay Packers
Who's out: Mark Tauscher, right tackle (Currently a free agent as he rehabilitates a torn anterior cruciate ligament)
Outlook: The Packers almost certainly would have brought back Tauscher were it not for the injury, and it's always possible he could return at midseason if and when he fully recovers. Until then, however, the Packers will have to determine if anyone on their current depth chart can handle the job.
Barbre will get the first chance. He's seen reserve action in 15 games over the past two seasons, mostly at guard, but has a mean streak that could serve him well in a primary run-blocking position of the offensive line. Some consider Lang, a fourth-round pick in 2009, a potential long-term answer.
Birk Sullivan Minnesota Vikings
Who's out: Matt Birk, center (Signed with Baltimore as free agent)
Who's in: John Sullivan (Sixth-round pick, 2008)
Outlook: The Vikings made a late run at trying to sign Birk but all along seemed prepared to pass the torch to Sullivan, a Notre Dame project who was one of the first players to report for offseason training this winter.
Sullivan doesn't have Birk's size, and it will be interesting to see if he can keep some of the game's top defensive tackles out of the Vikings' backfield. But from a mental standpoint, no one expects any difficulty with Sullivan's line calls or his capacity to otherwise handle the position.