But it won't help the team's porous defense in the short term.
Among the in-house candidates at the moment are fourth-round pick Anthony Hitchens and second-year pro DeVonte Holloman, who impressed the team last season when healthy, according to Calvin Watkins of ESPNDallas.com.
Coach Jason Garrett spoke optimistically of Hitchens before the news that Lee would miss the entire season.
"I think all positions have their challenges, no question about that," Garrett said. "There's a mental and intellectual challenge that comes with certain positions. Quarterback would be one of them. Center would be one of them. Mike linebacker would be one of them. But we feel good about the linebacker options that we have. We drafted Hitchens for a reason and we feel like he's a good football player and has some position flex. We'll see how he responds to the opportunity he gets."
Currently, the open market mainly contains aging veterans.
Ernie Sims attempted to replace the injured Lee last season and is familiar with defensive coordinator Rod Marinelli from their Detroit days. Former New Orleans Saints linebacker Jonathan Vilma could provide veteran leadership -- even if he's a step too slow.
UPDATE: NFL Media Insider Ian Rapoport reports that Lee also has a slight tear in his meniscus, per a source informed of the linebacker's injury. Rapoport added that the Cowboys don't plan on bringing in any outside veterans to replace Lee at this point. Linebackers DeVonte Holloman, Anthony Hitchens and Justin Durant will see snaps in Lee's absence.