Because GM Garth Snow was upset with a 4-4-3 start to the season, he wanted something to shake up the lineup. The Isles are probably an impact player away from being a serious Cup contender. While there isn't much by way of offensive prospects or minor leaguers in the organization that can make an immediate impact on a call up assignment, he wanted to check the market for something to spark the team. Sabres GM Darcy Regier was more than happy to oblige by dumping Vanek in exchange for more younger talent and draft potential. Buffalo has shown over the last few years that they are building from the ground up and that will eventually lead them to the Cup. At least, that's the model that seems to work in today's NHL (see LA, Chicago, Pittsburgh, etc).
The problem is that both guys are UFA's at the end of the season and the chance of either of them signing is probably slim to none (just ask Vanek's agent). Feasibly, this could be one-and-done for both players if an offer isn't tendered and neither player signed extensions as part of the trade. An offer, if it does come, is going to hinge heavily on serious play from both guys. I think Vanek might have a bit of an uphill battle because he will immediately have the pressure on him to perform. The Isles obviously feel that he can not only replace Moulson's production but eclipse it and create one of the best lines in hockey along with John Tavares. I don't think he will be a disappointment but even if he is a bust and the Islanders fall flat, they will surely retool and come back next season but without Vanek. That would mean that not only did they give away Moulson, but two draft picks as well and have nothing to show for it. Vanek would simply test the UFA market in the prime of his career and most likely get paid handsomely to do it.
As I mentioned, Vanek came out of the that huge double rookie class of 2005-06 after that 2004 lockout. He has over 1,400 cards on the market to show for it with a reference value in the range of $18K. His value is fueled by rookie auto's and memorabilia cards from the likes of UD Ultimate, The Cup, and newer issues like Dominion and Prime. Vanek cards tend to sell regularly, especially the nicer hits that are out here. Matt Moulson has only been in the league since 2007-08 and has almost 350 cards. His five rookie cards get some market traction but the bulk of his collection is centered on memorabilia and autographs. I think Moulson might get some notice now that he is in Buffalo and Vanek can only get better playing alongside hobby darling John Tavares.
We shall see if it's in the cards for either player. (pun intended)