Edgerton Hartwell has been an unsung gem on Baltimore's defense. Doug Pensinger/Getty Images

• Edgerton Hartwell, linebacker -- He didn't have his best year statistically as free agency beckoned (no sacks or interceptions in 2004), but the inside linebacker is a tackle machine who gets virtually no publicity playing beside the camera-seeking Ray Lewis. By the way, Lewis had just one sack and no interceptions last season, so Hartwell stacks up pretty well by that standard. With so many teams either playing or switching to the 3-4 defense, Hartwell will be in demand.

• Jermaine Wiggins, tight end -- Maybe it's coincidence, but Wiggins somehow keeps showing up on somebody's playoff roster. Wiggins blossomed into a go-to target in Minnesota, leading the Vikings with 71 catches -- which isn't easy to do when you're wearing the same color uniform as Randy Moss. With tight ends being so instrumental in offensive game plans these days, Wiggins should draw real interest if he makes it to the market.

• Jeremiah Trotter, linebacker -- Having already lost Trotter once via free agency in 2002, the Eagles are intent on re-signing their middle linebacker and defensive team leader. No surprise there. Philadelphia's defense took shape last year when Trotter was inserted into the lineup and quickly toughened up the run defense. He's not going to break the bank at this point in his career, but the Eagles would be wise to give Trotter enough green to keep him wearing green.

• Jason Ferguson, nose tackle -- Ferguson plays a position that figures to be in demand this offseason because of the number of teams making the move to a 3-4 defensive formation. Nose tackle is really the first position you make sure you have filled when you switch to a three-man defensive line. The 6-3, 305-pound Ferguson has the brawn to tie up blockers, and also can penetrate the backfield at times, as his 3.5 sacks -- and eight in the past two years -- will attest.

• L.J. Shelton, offensive tackle -- Yes, we know Shelton is not a free agent. The Cardinals are making him available via trade, and aren't likely to release him if one does not materialize. But for prospective suitors, there's a lot to like about the sixth-year veteran. He's on the block because he got in head coach Dennis Green's doghouse, but he's only 29, plays a pretty fair left tackle, and makes a very manageable $3 million per year. That's pretty low risk on all the key fronts.