His problem in Roubaix wasn't just his team, he wasn't strong enough either. He couldn't drop Hushovd and Ballan on the cobbles, if he would have been strong enough to do that, his lack of team wouldn't have mattered. Still, you're right, he could have won last year with a better team.
I'm not sure if we're gonna see a repeat of last year. Don't forget, the competition was scared out of their minds last year for Cancellara (after his clean sweep in 2010, and his dominance in the E3-prijs just before De Ronde), this year he will be 'just' one of the favorites, not the guy everyone races against to make him lose. I'm really eager to see if BMC can actually ride as a team, but we'll see more of that tomorrow.
I don't think signing a Roger Hammond would matter much, they've got a couple of guys of that level already. Cancellara deserves a domestique of a higher level.