I get the concern, but with Svech I think it's mostly a question of where he's at returning from injury. Physically, I'm sure he's fine, but he missed a whole year of hockey. Maybe he'll show up in camp and be up to speed and ready, but I wouldn't hold it against him if he needs some time this year just to get going again. That would be easier in GR. Then the Wings can call him up when the rust is knocked off.
With Jurco, I think he stopped playing the game that was making him successful. The first 20 or so games of his career, he was a force. He was fast, he was physical, he made things happen going to the net. He goes into Boston, tweaks his back a bit, gets some push back from the Bruins, and he just isn't the same afterwards.
Maybe he just didn't feel physically able to play that way any more, maybe he was a bit gun shy from the combination of injury and the Bruins pushing back, I don't know. But if Jurco would have kept playing that game I think he's still playing for the Wings and he's putting up some points.