Do yourself a favor, read this article by Dave Lozo, a name you probably now know well in the hockey world. This article was written right after the New Jersey Devils fired Peter DeBoer. DeBoer’s 2014-15 Devils started 12-17-7, and looked like one of the worst teams in the league while also being the oldest. It was a major problem, and Lou Lamoriello tried fixing it himself. The three-headed coaching monster didn’t work, but at least he did something.
One might argue the Devils should have done it sooner. The real problem was the plan of replacement.