The remainder of this post is clearly speculation on my part....
How it fits for Wake Forest:
Russ played for Wake Forest head coach Jim Grobe at Air Force. He's been a fairly succesful position coach at Ohio University and Syracuse. He also has one year of experience as the defensive coordinator at Syracuse. That was not a very succesful year for the Orange defense. I think he will be a very good position coach for the Deacons and fit in with one of the better coaching staffs in college football.
How it fits for Syracuse:
It certainly doesn't make sense. Why would a coordinator leave for a position coaching job at a lateral school? A couple of possibilities exist. But the one that I think is most likely is this. Greg Robinson has a lot of respect for Steve Russ. But Greg Robinson wanted control of the defense at Syracuse again. So instead of firing the coordinator, as he did with offensive coordinator Brian White. He told Russ, take your time, find yourself another job. Or if you'd like you can stay on as the linebackers coach. But I'm controlling the defense next year. So when Russ had this opportunity he took it. I don't think the Orange hires another defensive coordinator. Since Robinson has his guy, Mitch Browning to run the offense, I think he feels he can resume his duties as defensive coordinator. Therefore, he just needs a linebackers coach. Expect that hire to be announced within the next few weeks.