The anatomy of results- do Consultants deliver?

Was reading an extremely provocative discussion on David Maister's blog on the value consultants bring to the table. I have had violent debates with my colleagues on the extent to which we as consultants can take responsibility for client's result. I have always found it to be an extremely arrogant (if not salesman-like claim) when consultants claim of delivering results (as in growth, profitability etc.) without acknowledging the contribution from management or the circumstances. I am a little conservative on such promises and claims and usually come across as being defensive but i strongly believe that we consultants are limited by three barriers-

1. Blinded by our specialization- there is much more to an organization than what we are good at!
2. Limited by the vantage point- the CEO/COO vantage point is just not available to us to realize the many fine lines that they have to walk in managing the entire organization
3. Protected from hidden agendas and political pressures which are such an integral part of any organization.

Having said that, i do believe that we provide enormous value in creating a high level of understanding in an organisation which primarily comes from four factors-

1. Ability to singlemindedly focus on an issue- just a function of time.
2. Cross category knowledge which is able to see many different perspectives simultaneously compared to those who have spent a lifetime in a particular environment
3. Objectivity of an outsider.
4. A lifetime of experience in a domain (particularly applicable to niche areas like mine (brand strategy) where a lot of time and energy can get wasted by not seeing the broader context in which a brand is getting built.

I make it a conscious effort to cultivate a deep respect for the smallest entrepreneur or even a manager of a modestly sized team for what they are up to. I may see a lot amiss given how many organizations i study in the course of the work but nothing can take away the credit from a person pulling together a bunch of people to deliver value on an everyday basis, however small it may be.

So the context for a consultant in my opinion has to be one of a servant-leader whose interpretation/ findings/recommendations are more a stimuli to aid a management's self investigation, rather than truth about their organization.