Maybe it's because it's a little more common in American sports, but it's not unusual for the head coach of a team to fire offensive coordinators or various other people that do the day to day management.
Yes, it's partially to deflect the blame and ultimately, the manager/head coach is responsible for all things in the team, but over here, it's not unusual for the manager/head coach to fire some of his coordinators or assistants from season to season. Sometimes, they really are doing a poor job.
Now, it's unusual to do it in the middle of the season, but it's not unheard of. I don't know. Maybe that's why I don't see it as such a huge deal