Free-agent fit: Linebacker

Fourth in a series on free-agent fits at various positions leading into the start of free agency March 12.

Position: Linebacker

Players under contract for 2013: Jerod Mayo, Brandon Spikes, Dont’a Hightower, Dane Fletcher, Mike Rivera, Jeff Tarpinian, Marcus Benard

Level of need: Low-to-moderate

Projected top targets: Jonathan Casillas (Saints), Brandon Siler (Chiefs), Tracy White (Patriots)

Why Casillas fits: The 25-year-old Casillas (6-1, 227) is considered a solid special teams player who might factor into the mix in sub packages. Given the Patriots’ strong returning group, any linebacker addition would have to project to a core special teams role.

Why Siler fits: Having played under former Patriots coordinator Romeo Crennel last season, Siler (6-2, 239) could add depth behind Brandon Spikes in the middle. The 27-year-old Siler played in college at Florida.

Why White fits: One of the Patriots’ core special teams players since 2010, White also showed up at times on defense in a niche role. At 31, he’s closer to the end of his career.

Other names of note: Connor Barwin (Texans), Chase Blackburn (Giants), Justin Durant (Lions), Dannell Ellerbe (Ravens), Tavares Gooden (49ers), Quentin Groves (Cardinals), Jason Hunter (Broncos), Niko Koutouvides (Patriots), Manny Lawson (Bengals), LB Rey Maualuga (Bengals), Erik Walden (Packers), Phillip Wheeler (Raiders), Tracy White (Patriots)

Market conditions: There doesn’t appear to be a lot of three-down options on the market, which makes sense because those players are rare. The Patriots are well stocked so any addition would likely be with special teams in mind, first and foremost. Overall, this looks like an underwhelming position on the market.

Questions to answer at position: Is Spikes better suited as a true two-down linebacker who comes off the field in passing situations? … Knowing that players often make their biggest jump from their rookie season to their second season, what does this mean for 2012 first-round pick Dont’a Hightower? … Does top reserve Dane Fletcher regain his previous form after missing the 2012 season with a torn ACL? … Would the Patriots consider a return to strongside linebacker for defensive end Rob Ninkovich?

YOUR TURN: Which of these would you like to see in a Patriots uniform? Share your thoughts in the comments section of this blog entry.