That only works if you look at Babcock's tenure with the Leafs in isolation and pretend Babcock never coached anywhere else. Because claiming he "needed to teach the young Leaf players to play dump and chase" does not work when it's TEAM CANADA you're talking about...
And despite that, Babcock's Team Canada, with some of the best players in the world... Were playing dump-and-chase. So were all of his Red Wing teams. So did all of his Anaheim teams. Fact is, Babcock wasn't trying to teach the young players on the Leafs to play dump and chase because they needed balance; he was teaching the players to play dump-and-chase because Babcock insists every team he coaches play dump-and-chase, talent level be damned. And that's what made him a good coach for the beginning of the rebuild, but a terrible one as the rebuild progressed and the Leafs started to amass more talent. This team simply SUCKS when they try to play dump-and-chase and only dump-and-chase. They don't have the players for it, and even now with Keefe as the HC, you can see that when the Leafs fall back into dump-and-chase (an expected result after four years of the HC insisting on it being the go-to strategy), they look like complete dog ****.
An argument can be made that they'll have to adjust the roster to get a few guys capable of doing the dump-and-chase, because in the playoffs it's more likely to be successful. But what's not arguable is that the Leafs cannot do it as they are currently assembled, and trying to force it on a roster not built for it is squandering the roster's talent.
As I said in other topics, the Leafs should try to use an attacking possession game and see how far it takes them, as teams like Detroit and Colorado have done in the past. If they still aren't moving forward with it, then the balance of the roster needs to be adjusted.