I think you're confusing "shattered" with "was mean to". Since MT and MB came on board both Eller and PK has grown into stars. PK won the Norris and is being pushed to be better (and he's getting better too), and Eller was sat early, then established himself as the no. 2 c (this year he's become the no. 1).
Leblanc and Tinordi are still rookies that will take time to develop. Just because MT and MB have taken a somewhat hard line with these guys doesn't mean they've shattered them.
And what do DD, Briere, Diaz, Gorges, Gionta, Bouillon and Co have in common? They're veterans. These guys get treated differently by coaches than rookies. Always have, remember JM and co?
Have some faith, these guys definitely know more about hockey than you or I. They'll make some mistakes, but generally they know what's what. MT was brought in because he took a team of young players from the basement to the finals. He has learned how to coach young, elite players, and make them better. I think PK and Eller are further proof of that.