I would guess that, by now, he’s realized he’s not going to be a HC in the NFL. So, he took a job as a position coach. I think there are 2 possible reasons to do so:
1. He understands his ceiling is as an offensive coordinator, and he views this as a step on the path to that.
2. The job is a lot easier than being an OC, with less responsibility, and he’s just mailing it in these days.