Generally, marketing firms can be classified as either upstream or downstream. Downstream firms are tactical. They offer something specific: "We do web sites," for example.

CZ, however, is an upstream firm. While upstream firms may appear to offer similar services as those downstream, upstream firms are strategic. They ask different questions:

“What is your point of difference?”
  “Who are your competitors?”
“How does the reality (experience) of what you provide need to change?”

CZ's sweet spot is its "demand generation" strategy. CZ designs the strategy and also executes the campaigns that grow your client list.