Menzinger
Kessel4LadyByng
And yet studies on the subject find virtually no impact.
The stuff I've read suggests that coaching changes mid season will have little to no impact.
Longer term not so much. Again, look at the Ducks - with Carlyle they were a steadily declining team. He's fired, the team comfortably makes the playoffs the following season.
And in this thread - using a 1/2 season sample size of Detroit when they've gotten incredibly high q
Goaltending (likely very unsustainable long term) to show Babcock made no difference to that Irganization is a very questionable argument.