Something to think about as the Rams pursue a new head coach, and by extension new coordinators, is what kind of schemes and systems they'll run. A PD article the other day discussed the trouble facing scouts as they review potential draft picks and free agent talent without knowing for sure what kind of look the Rams will bring to the field next season. I'm not convinced we'll see dramatic shifts in basic systems the team uses (more on that later), but with the head coaching search leaning heavily toward defense oriented candidates, it's worth looking at what schemes each guy currently uses. Much of this depends on the next defensive coordinator too.
As an assistant/linebackers coach, Green Bay's Winston Moss, already lined up for a second interview with the Rams, was an integral part of a system using a 4-3. There's some incestuousness between Moss and the Rams; Moss served as Haslett's linebackers coach with the Saints. Moss is your guy if continuity is your thing. His approach on defense would be fairly close to what the Rams use now - a blitz heavy 4-3 with man coverage in the backfield. Obviously, the Rams have some major personnel holes to fill even if they opt to keep the current system, but Moss might be capable of getting this outfit to work like it should. I think he's also a candidate for defensive coordinator, especially if the team retains Haslett.
Viking defensive coordinator Leslie Frazier uses a 4-3 in MInnesota with more of a Tampa-2 zone approach in the backfield. Because the Rams corps of defensive backs is likely to see heavy turnover, the different approaches probably don't matter all that much in Frazier's case. It does impact the kind of cornerbacks the team will be scouting.
Baltimore's Rex Ryan uses multiple fronts, but it all starts with the 3-4. The process of changing from a 4-3 to a 3-4 is the subject of a later post,
As Miami's secondary coach, Todd Bowles used man coverage to decent results, collecting 18 INTs, with a group lacking any kind of shut down/superstar corner. Miami is widely believed to be interested in keeping Bowles, and could have him in mind for their next defensive coordinator. With Miami and Dallas prior to that, Bowles was part of a 3-4 defense.
Those are the three confirmed head coach candidates with a defensive background. Steve Spagnuolo and Jim Schwartz, both supposedly being considered, are the other current defensive coordinators on the Rams list (maybe) and both run a 4-3 defense. Devaney's familiarity with Schwartz may have pushed an initial, getting-to-know-you interview off the table, but I'd be paying more attention to the four guys mentioned above.
Oh, and don't forget about Haslett. He runs a 4-3, as you well know.