I personally believe Kulemin is a poor substitute for Moulson.
as much as I love Kulemin, Moulson is a much more of an offensive threat. Look at his pure-offensive numbers, and it blows Kulemin out of the water. Though to a championship team, I'd take Kulemin due to his physicality, mentality and work ethic.
Nevertheless, I wouldn't have wanted Vanek. We have a solid team, and it is only going to cost our team (in terms of current chemistry) if we gave up someone that's on our roster. In terms of prospects though, it might've costed us even more, simply because prospects are prospects.
All in all, it's a good move that they did not trade Vanek (I did not even mention his cap hit and his "desire" to play for the Wild).