I'm going to put cap hit part of the equation aside for this piece. Instead I'm looking at the Panthers' ‘needs' side of the equation only; needs as simple as actual bodies to fill out the depth chart and ‘needs' regarding the current talent level at the position.
Let's start with the obvious and go from there in no particular order:
The Panthers have six (6) defensive tackles on the roster but only one starter remains from the 2012 squad, that being soon-to-be free agent Dwan Edwards. The remaining five (Fua, Neblett, Kearse, Cole, Chandler) are otherwise not-ready for prime time or in the case of recently signed Colin Cole, has been away from prime time for 2 years. Short of Sione Fua becoming a legit starting nose tackle the Panthers need to upgrade the talent at both DT positions. Hence why DT is the most common position mocked to the Panthers. The Panthers might still do that but I'm hoping they first add a mid-tier free agent, like the space-eater mentioned here for instance.
Assuming Captain Munnerlyn gets courted to another team in free agency that would leave the Panthers with five (5) CBs on the roster, (Norman, Thomas, Dockery, Ness, Hixson). A couple of those do offer some promise but they also only have 11 seasons of experience between them (2.2 avg). A veteran presence would be welcome in this group.
A player like the Steelers Keenan Lewis might be the best signing of the offseason for the Panthers:
Free agency primer: Ranking the cornerbacks - NFL.com
Lewis matured last season in Pittsburgh. He led the NFL with 16 passes defended and improved in coverage as the campaign progressed. In this group, only Smith played more snaps (1,068) than Lewis (943).
Otherwise we might be able to squeeze something out of Antoine Cason, Quinton Jammer or Greg Tolar
The Panthers have plenty of bodies to plug in here, both young and old, experienced and inexperienced. Overall though there is little hope to improvement beyond rookie LT Amini Silatolu. The experienced players Handgartner and Pollack, seem at the end of their shelf life. The young guys Wells, Hicks and Z Williams have not shown much if anything at all.
Here's a couple mid-level guys the Panthers might be able to afford:
Free agency primer: Ranking the top offensive linemen - NFL.com
Garner is believed to be seeking a contract worth $3 million per year after proving capable of playing both guard and tackle. ... Thomas is expected to test the market after showing well as an injury replacement for Logan Mankins and Dan Connolly last season.
The Panthers go nine deep at WR yet in my view only three of those guys are safe to be on the roster in late September, that being Smitty, LaFell and Louis Murphy. Though I think there is upside in guys like Adams, Bryant and Gettis a veteran free agent looking for an opportunity could beat out any of the bottom five players. Especially if it's a vet like Ramses Barden, whom I admit I am biased towards simply from week 3 last season. I'm thinking a red zone target is what Newton could really use the most.
Though the Panthers seem set with their starters in Jordan Gross and Byron Bell the depth behind them is in serious questions. Garry Williams might just be better suited for RG and Bruce Campbell, do we know what we have?
The picking are slim for OTs in free agency but there is one guy who might be a good fit, a guy we know well: Geoff Schwartz. He is a better run blocker than pass blocker but he would represent a nice OL back-up at both RG and RT.
Update: Hat tip to Agent Green for pointing out back-up QB is a solid need I had left off, so I've added it.
Assuming Derek Anderson will be leaving via free agency that leaves Jimmy Clausen as the back-up. Whether you think Clausen has upside or not it's hard to say he's a fit for the 2012 Carolina offense. Maybe new OC Mike Shula changes that in 2013 but I'm thinking we want a back-up that is more in the mold of the starter. A free agent like Pat White might be a cheap option to consider.