With more than a week of free agency in the books, let's check in on the Detroit Lions' needs on defense.
Still a top need
Defensive tackle - There's no way the Lions can replace the talent they lost at defensive tackle with Ndamukong Suh and Nick Fairley departing, but trading for Haloti Ngata was a good way to start rebuilding this position. Signing someone under the radar like Tyrunn Walker was also a nice move, but the Lions still have a starting spot up for grabs as far as I'm concerned. Maybe Walker will win that starting job, but even so, that would still leave very little depth at this position. As a result, look for the Lions to spend an early draft pick on a defensive tackle, and it wouldn't be surprising if they eventually decide to add another veteran here for additional depth.
Cornerback - With Rashean Mathis unsigned, the Lions currently have an opening in their starting lineup at cornerback. Considering how well Mathis played last year, that's not a good thing. My feeling is that Mathis will ultimately be brought back, but until that actually happens, this will continue to be a top need. And even if Mathis is re-signed, the Lions will need to start thinking about his eventual replacement, and they could also potentially be in the market for an upgrade at nickelback.
In good shape
Defensive end - Restricted free agent George Johnson hasn't signed his tender just yet, leaving the door open that another team could sign him to an offer sheet. Chances are he will be back with the Lions, though, and even if he's not, there is plenty of depth at defensive end, especially with Darryl Tapp being re-signed. It's looking like the Lions will be in a situation again this year where a player deserving of playing time (Larry Webster, for example) may not even have a chance to see the field because there is so much depth here.
Linebacker - With the Lions re-signing Josh Bynes and getting Stephen Tulloch back from a torn ACL, linebacker could be the deepest position on the roster, especially if Kyle Van Noy takes a big step forward in his second year in the league.
Safety - The Lions made a great move to re-sign Isa Abdul-Quddus, who is a valuable backup who performed well when called upon to occasionally start last season. With him back in the fold and Glover Quin and James Ihedigbo still starting, this is another defensive position that appears to be set. Perhaps the Lions could add a player here to eventually take over for Ihedigbo, but I wouldn't exactly call that a need at this point.
Kicker, punter and long snapper - No, I haven't forgotten about special teams. With the Lions re-signing kicker Matt Prater and long snapper Don Muhlbach, they are already good to go when it comes to their specialists. Chances are an undrafted kicker and punter will be brought in to take some of the reps in training camp, but from the perspective of the 53-man roster, the Lions are set on special teams.