i do agree with big phil here that certain aspects of modern training probably curb creativity as much as they encourage it.
power skating, for example, can ideally train a player to be more nimble, and be more able to execute manoeuvres that we would associate with the edgework of, say, orr, perreault, savard, datsyuk, karlsson, etc. but how many kids get that kind of skating instructor or coach? how many more get the kind that limits you to your ability to totally and completely master one of three or four aspects of skating? or maybe even just "huge burst" straight line acceleration?
i also generally agree that too much drilling at a young age at the expense of just letting kids scrimmage does more harm than good.
that said, i also think if mario or esposito or whomever took better care of themselves they probably could have gotten even more out of their abilities. it's not like eating steaks and drinking wine was giving them superhuman hockey sense.
but of course you have to do it the smart way. i remember one summer brent sopel came back with an extra twenty pounds of muscle and was horrible because he lost all his mobility.