Okay but work with me here...
If the going theory is that our D prospects are good to very good and young defenseman are coveted in the marketplace, why couldn't we move a young dman in 2-3 years for some offense to replace the loss of Pastrnak?
The point you make is that in 3-4 years losing Pastrnak will likely hurt, and I'd agree. But for the next 3-4 years, we suck. So, I'd rather shore up the next 3-4 years by adding a real dman, then IF these D prospects end up as advertised, we have an excess in a coveted position from which to deal for offense. And ultimately I'd much rather be in the market for offense than defense.
Well first, even though Boston has a nice stockpile of young D, they are not all going to pan out, heck even half of them probably won't ever play, but there is enough quantity among the quality that you should find 2, maybe capable NHL D-men out of the 10 or so guys they have in the system. But it's not likely they'll have a overabundance of which to deal from.
And if they did, GMs should never assume that what their team needs will be available in the marketplace 3-4 years out when making deals today. Heck they shouldn't do it making deals assuming what's in the marketplace right now. Go see Chiarelli's quest for a RWer in 2015, or Sweeney's quest to find Defensive help since last year. Making a deal to make another deal rarely works, works even less when your planning on making that deal 2-3 years out with no knowledge of what the trade market will be at that time.
Everyone talks about how coveted Centermen and D-men are in the trade market. You know what else is coveted. Game-breaking wingers, home-run hitters if you will.
Think Kane, Benn, OV, Tarasenko, Kessel, Gaudreau, Perry, Kucherov, even our own Marchand. Very difficult, not impossible, but very difficult to acquire.
Pastrnak has that game-breaking potential. I can't guarantee he ever gets there, but he's the only guy in Boston's system under 25 that I'd be willing to place bets on being a top-level game-breaking winger. Heck forget just wingers, he's the only guy they have with that type of potential at forward. Sorry Senyshyn, Debrusk, etc. etc. are all fine prospects, but I don't see any of them reaching that upper-echelon that Pastrnak can. And you need at least a couple of those guys to compete. Having a roster chaulk full of 15-20 goal scorers is nice and all but you also need those level of guys like the names mentioned above who can score, create, and produce offense on those nights when no one else can. Even when Boston was winning cups you had Krejci and Horton who could break open a game offensively when no one else could.
And let's be honest, Jacob Trouba isn't going to be the difference between sucking and not sucking. Now he should be able to get a near-miss DNQ team like Boston a spot in the dance come playoff time, but he's not going to take a bad team and make it very good.