For Cavendish to win a group sprint there first needs to be one; he needs his team close down the breakaways and to a lesser extent keep the pace high to prevent counter-attacks.
HTC failed in this tour on two stages:
Stage 4 where Cavendish blew, their train was 1 man short for the distance they tried to take it out from, hence Cavendish wasted a lot of enegy battling Hushovd for position before opening up too soon (i called the result 1.5k out).
On Stage 13 HTC didn't get enough men over the climb to drag Vino back (although they were 2 men down and Grabcsh was done for; Rogers, Sivtsov and Martin (who i expected more of) needed to be prepared for a massive effort). This is where i think Van Garderen could shine next year (taking Montfort's place) and if you add Goss for Hansen you have the ultimate stage winning machine.