Two of the Lions’ more interesting free-agency decisions come in the secondary, with FS Louis Delmas and CB Chris Houston both slated to be unrestricted free agents. The 25-year-old Delmas is regarded as one of the better players at his position and one of the keys to the Lions’ secondary, but he’s been bothered by knee injuries the last two seasons. Houston, 28, is a proven performer at a position teams increasingly covet in a pass-happy league. The way we hear it, the Lions figure to try and retain Delmas. Houston’s future is a little tougher to read because of the sometimes-overheated market for cornerbacks, we're told. The Lions drafted three cornerbacks in April (Bill Bentley, Jonte Green, Chris Greenwood), a nod to the need to restock the ranks at the position. Were Houston to depart, the Lions’ CB depth could again loom a concern. The club’s safety depth could also have to be addressed with Delmas’ deal expiring and SS Amari Spievey suffering multiple concussions in 2012.