If you watch 2010, the last time Tyler did Qatar/Oman, it was a very similar story, lots of 3rds and 4ths. Or even going back to Tour of California in 2008, where he was 3rd in the prologue, but nowhere in the sprints. Tyler has never been one to be overly fit in february, as he spends much of his time cross country skiing in the winter. he develops a robust fitness for the classics, but isn't that speedy. Its a typical pattern for him, so I'm not too worried.
But, does he win on instinct? No. When Tyler wins, it's because he is blatantly the strongest. That's why it's crucial to have a very fast lead out train around him, as he doesnt do the duck and weave as well as Cav. He's just a very strong rider that likes to sprint, as opposed to just being a sprinter.
For me, Cancellara is the major threat in Roubaix. If BMC plays the card pulling for one leader, then it plays very well to Cancellara, as he doesn't have to rely on his own team, which isn't as strong for Roubaix. His team couldn't hold the race together in 2011, and he had to do a lot of work early on his own, which is why we won. But if BMC holds it together for him, he'll be lethal on the last 3 sectors of pave, where teamwork is out the window, and legs are what counts.