I said it last year and I'll say it again. In my mind, Cavendish has the best jump of anyone in the sport. Add that to a very well-rehearsed lead out train and that spells success more often than failure.
Garmin consistently rides to second place for two reasons: they still can't organize a proper lead-out train, and Farrar isn't from the same mold as Cav. He doesn't have a super-fast first jump but may be a higher top-end guy, more in line with Ale-Jet and Thor.
Today's sprint captured both those points very well, I think. The final 1.5K was a mess for everyone. Teams are on to the idea that you have to swarm HTC over and over to disrupt their train, but over and over, the HTC and Lampre boys were able to re-establish their leadout where Garmin was left all over the place (and if you listened to Robbie Hunter after the finish, thouroughly confused).
The other thing that was clear again, and you saw this over and over last year, is that Farrar is better able than most to react to Cav's acceleration, but needs more real estate to get up to speed. It often seems like Cav is running the 100 meter dash, when Farrar is running the 200. Unfortunately, the end result is moving up from 5th or 6th wheel to no better than second. He closes ground, but it's obviously too late.