The problem with Digs is that he doesn't offer anything new. Landry is a hitter. Smith is a hitter. Digs is a hitter. Even Tracy Wilson is more of a strong safety/hitter (is he still on the team?). We need a coverage safety. If Digs is willing to compete for one of the last roster spots on the team as primarily a special teamer, I'd definitely consider it, but I doubt he'd want that.
The one logical scenario in which we bring back Digs, is if (when) we bring in another safety to play with Landry, and Smith becomes unwilling to take a paycut to be a backup. Obviously at 2 million this year Smith would be overpaid to be a #3 but that number isnt terrible, however next year when his salary baloons to 3million it becomes a big issue. So if they wanted Digs to play behind Landry/Whoever id be cool with that, although I think id personally rather just sign a late round flyer (5th rounder), who at least has upside and possibility the ability to cover.
