Lions back-to-work FYI

Readiness factor: Coach Jim Schwartz has maintained the same offensive and defensive schemes since arriving in 2009, minimizing the mental cram factor in training camp. But significant transitions loom at several positions, and they will be rushed in less-than-ideal situations. The Lions need to establish three starting defensive backs, two linebackers and will also need to find a balance for their running back duo of Jahvid Best and Mikel Leshoure.

Biggest challenge: I think someone once said that cornerbacks don't grow on trees. (Neither does money, I hear.) We've been over this issue before, but here are the facts: The Lions' top two cornerbacks currently under contract are Alphonso Smith and Nathan Vasher. Is that their plan for 2011? Will they be aggressive enough to land one of the few starting-quality free agents available? Is veteran Chris Houston more likely to re-sign? Perhaps, but the Lions have a complex problem to solve in quick fashion.

Obligatory Stafford reminder: It's been well-established that quarterback Matthew Stafford's right shoulder has healed after January surgery. He has looked buff during offseason workouts and is ready to resume his role as the Lions' franchise quarterback. At 23, Stafford is about the same age as 2011 rookies Jake Locker, Christian Ponder and Blaine Gabbert. But two years of injuries have put Stafford into something close to a make-or-break season. He needs to stay on the field.

Key players without contracts for 2011: Defensive end Cliff Avril, cornerback Chris Houston, running back Kevin Smith, quarterback Drew Stanton.