I think that's almost become markov's most important asset. He's been a top tier defenceman, he knows what it's like to play in that role in Montreal, perfect for showing Subban the ropes.
My only problem is that, Subban grows at an explosive rate, and I wonder if Markov will have anything to teach him in a year or two. By that time, my hunch is that markov's game will have slowed even more, an his value will be no where near what it is now. That's the only reason I wonder if trading him would be a good idea. I hate watching an assets value pine away, when a good return might have been possible before. This goes for Gionta as well.