The correct question on Rosen is where does he fit? That currently doesn't have an answer, but who knows what'll change over the next 2-3 years. That's why he's the best value/easiest to envision in trade scenarios.
Saying Rosen is bad/a wasted pick, however, is simply nonsense. He was one of the Swedes' best players at the WJC, outplaying guys like Lysell, Lekkiermakki, Ohgren. He's had a solid D+2 season, first in America, after a rocky D+1 with injuries.
He has speed only Savoie can match org wide, and a NHL-level shot. There's dev work to be done, he isn't close to the NHL, but he's far from a 'wasted pick' He's an A-tier prospect that might be expendable for D/G help.