Yeah, so congrats to Cam Ward for being the next NFL QB who is going to be jerked around with new coaches and new offenses regularly early in his career.
Here's a controversial take (well probably not here because no one cares about the Titans), but the Titans current QB coach, Bo Hardegree, is the one who was the QB coach for the bad versions of Derek Carr, Ryan Tannahill and Will Levis, while also working on offenses that oversaw the bad versions of Mac Jones and Sam Darnold early in their careers. Meanwhile Brian Callahan was the QB coach for Mattew Stafford in his prime and the OC for Joe Burrow while being an assistant on the Broncos when Peyton Manning was there.
Background out of the way, if the Titans want a shot at salvaging Ward, they should have considered demoting Brian Callahan to QB coach, who at least has worked with elite QB talent before. It would have been awkward but could have perhaps been salvaged by promoting his dad to interim HC. His dad did coach a team to the Super Bowl after all, he's qualified for an interim job. I'd guess he won't take it now that his son was fired though.