Schürrle's movement, Stoke's problems with build-up play
Chelsea were dominating Stoke City's right side as well. Cameron and Walters struggled to bring out the ball, and were often dispossessed by Azpilicuata, who received additional cover from at least one Chelsea midfielder. Hazard could often get behind Cameron with these balls won high up the pitch. He had several chances to take on Shawcross one-on-one, but he usually passed on the opportunity, passing the ball back to midfield.
Such instances showed what Chelsea's main problem was in the early stages of the game. Even though they got into dangerous positions, they were complacent, and not taking enough risks. They either didn't make the most of potentially rewarding situations, or missed the chances they had. Chelsea were complacent, which had a major part to play in their loss.
Stoke City switch to a more direct style
It would have made more sense to ask Crouch to drop a bit deeper, and play against Mikel. Crouch could have been used as a wall passing option, or he could have pulled one of the defenders out of position, opening up space for Arnautović to run into.
Even though Schürrle equalised on the half-volley only minutes after, Chelsea were far from convincing. As Stoke City played more long balls, their full-backs didn't have to push up with the attacks. Chelsea had less space in the final third as a result.