The Los Angeles Chargers made some key re-sigings in free agency before the draft, highlighted, but not limited to, getting Khalil Mack back under contract.  But the roster churn after Year 2 of the Jim Harbaugh era was always going to be immense. Entire positional groups, like the interior of the offensive line, were always going to get replaced. Pieces of a defense that had a coordinator change moved around, too. And Mike McDaniel coming over as offensive coordinator meant a revamp across the depth chart.  Looking at it now, the list of Chargers free agents who still don’t have a new home says more than almost anything else.  NFL free agents list filled with Chargers Andre James | Kyle Terada-Imagn Images In the wake of the NFL draft, the notable remaining free agents tend to find homes between that first week and into training camp.  Still, it feels like the Chargers have more free agents left on the open market than most other teams.  Take, for example, Mekhi Becton.…