No contracts were signed.
This is technically true, though it barely matters. It's like splitting up with your new wife after the wedding ceremony but before you made it to the courthouse. Half his staff was already hired, he probably had an office and a parking spot with his name already on it and a hotel booked for the next month. It would have been a disastrous mess if Irsay hadn't kept the assistants who actually had already signed contracts.
Hard to place all the blame on McDaniels though, hopefully this is the deciding factor in changing NFL hiring rules, though to what is unclear. Falcons had to wait until February to hire Dan Quinn, and I read somewhere recently that the last several assistants accepting a job after the SB have all lost the game (Quinn, Shanahan, McDaniels/Patricia, Bill O Brien come to mind). McDaniels has every right to do what's best for himself, and while the way he did it was totally a Dick Move, staying with the Patriots vs heading to a dysfunctional Colts organization is a no brainer. Can't really blame the Patriots either, they are obviously better with him, though I honestly suspect if it was to a team/owner Kraft liked he wouldn't have tried so hard to keep Josh.
Hopefully it works out for him in New England, because I certainly can't see anyone else trying to hire him as their head coach for a long time to come, which is exactly what people said last time he was a head coach.