Why is the success of consulting projects so hard to prove?
The short answer
Consulting success is hard to prove because impact appears after the mandate ends, and at that point no one measures what caused it. There is no industry-wide survey on how often this measurement happens. What is documented is that 44 percent of transformations land in a grey zone: value is created, but targets are missed.
There is no statistic for how often consulting success is measured
I looked for it in several places: BDU, Luenendonk, Source Global Research, German and English trade press. There is no publicly accessible survey on how often the success of a consulting project is measured at all.
That is remarkable for an industry that lives from measurability and regularly builds KPI systems for clients. It is also structural rather than moral. The moment at which impact appears lies outside the mandate.
A project ends with the final report. The change for which it was commissioned begins afterwards. From then on, no one in the room has a strong reason to attribute the change to a specific recommendation.
44 percent land in the grey zone
The claim that 70 percent of transformations fail has circulated for decades and has no solid data basis. Mark Hughes traced published references back to their roots and found no robust empirical evidence for the statement (Journal of Change Management, 2011).
A more useful analysis comes from BCG. 30 percent of examined transformation programs achieved their targets with sustainable change. 44 percent created value but missed targets and left little lasting change. 26 percent remained below half of the intended value (Boston Consulting Group, 2020).
The 44 percent are the interesting group. The normal case is the grey zone: something happened, it was not nothing, but it was not enough and did not last. For a consultancy, that is the hardest outcome to tell.
The market has already answered
Accenture generated revenue of 69.67 billion US dollars in fiscal 2025. Consulting accounted for 35.11 billion with 6 percent growth; managed services for 34.57 billion with 9 percent growth (Accenture, audited annual reporting, 2025).
The split is almost 50/50, and the implementation and operations side grows faster. That does not argue against consulting. It shows where the proof point has moved.
Managed-services contracts carry metrics inside them: throughput times, availability, unit costs, often reported monthly and contractually defined. A consulting mandate ends with handover. What happens afterwards is captured in a different system by different people.
The IKEA effect explains why concepts are overrated
People value things more highly when they have worked on them. In Norton, Mochon and Ariely’s experiments, people who built objects themselves paid more for them than uninvolved third parties did (Journal of Consumer Psychology, 2012).
For consulting projects, this means two things. The team overvalues the concept it has created, and the client who worked in workshops often does as well.
But the effect depends on completion. When people were stopped before completion, the valuation fell sharply. A concept without implementation is the unfinished instruction manual. It creates no durable attachment for the client, however good it is.
The final report is finished work for the consultancy. For the client, it is the moment when the work begins. The evaluation that decides the next mandate is the client’s.
The proof is created at the start of the project
Whoever asks at the end of a mandate what the work achieved reconstructs a connection. Whoever records that connection at the decision measures it. The difference is three entries before the first analysis starts: target, expected value contribution and stop condition.
Those entries should belong to the client, not to the consultancy. The consultancy suggests how success could become visible; the company decides and measures. Otherwise, the final output is a success claim with a letterhead.
BizzPlAI is built for this as a Strategy Execution System. The expected value contribution of a measure is recorded at the decision and remains findable after the mandate has ended. Twelve months later, the realized contribution can be placed next to it in the client’s numbers and system.
The test is simple. For your last three completed mandates, state which metric changed afterwards and by how much. Where that is impossible, the problem may not be the impact of your work. It is the absence of proof, and that decides the next project.
Common follow-up questions
Why is client satisfaction not enough as proof of success?
Satisfaction is measured at the end of the mandate, while impact appears later. A client can be very satisfied with the collaboration and still see no result change one year later. That later assessment decides the next mandate.
How can impact be measured without patronizing the client?
By defining the impact measure together at the decision point and making it belong to the client, not the consultancy. The consultancy proposes what success could be recognized by; the client decides and measures.
What can be done when a finished project left no metrics?
Retrospectively, little can be rescued because baselines are missing. For completed projects, a conversation about observed changes is better than nothing, but it is not robust evidence. The next mandate needs the assignment from the start.
Sources
- Flipping the Odds of Digital Transformation SuccessBoston Consulting Group, 2020
- Do 70 Per Cent of All Organizational Change Initiatives Really Fail?Journal of Change Management (Mark Hughes), 2011
- Accenture Reports Fourth Quarter and Full Year Fiscal 2025 ResultsAccenture plc, 2025
- The IKEA effect: When labor leads to loveJournal of Consumer Psychology (Michael I. Norton, Daniel Mochon, Dan Ariely), 2012
- Investigating the Not Invented Here (NIH) syndromeR&D Management (Ralph Katz, Thomas J. Allen), 1982
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