He couldn't on a team that breeds defenders for a living. Devils are so defence oriented, do you really think they give up a guy they believe can turn into a solid player for pick? Given the avs history of developing defenders do you think they can turn him into something? I wouldn't bet on it, he'll probably be out of the NHL by next season.
It is all about the type of D man he is. An offensive D man is not something NJ is known for developing. Even journeymen D men are not what you look to NJ for. They typically develop strong shutdown first D men that play well in a system...and when they leave NJ they struggle.
The Avs history of D men is developing offensive first D men, Ozo, Liles, Barrie, and to a lesser extent Skoula. They also are great at getting water from rocks like deVries, Klemm, Holden, Finger, Clark, Miller, and so on as you list journeymen.
I don't expect Gelinas to turn into the next Rob Blake, but he very well could be the next Miller, Klemm, or even just a Holden. That solid depth D man who fits a certain job on the team. And that is what the Avs need. A complement to the already existing core. He has a heavy/hard shot and is perceived to be a PP specialist...two things the Avs need improvement on.
Gelinas might just not be a systems based D man...and good for him, Colorado is about as opposite of NJ as it can be.