Yeah, it's amazing how the goalposts can be moved to fit a narrative. Babcock pulled of a minor miracle in a lot of those seasons getting Detroit into the playoffs, considering age and injuries to those detroit teams, and in his first few seasons with the Leafs, playoffs were either impossible, or the finish line - like the first round loss to Washington year.
The last two seasons have seen a lot of young leaf players develop under babcock, and despite extremely weak defense personnel, had good regular seasons. Losing to Boston in the first round is more a matter of circumstance than failure; it's not Babcock's fault the Kadri put the team in such a hole matchup wise, and being bounced by a team in 7 games that was ahead of them in the standings and had home ice, and almost won the cup isn't exactly absymal failure.