In my opinion, one of the main reasons
IT projects fail is the inability of translating business requirements to
IT solutions. Thus, the role of business analysis is to bridge the gap between
business (management) and IT (development).
See the communication/know-how diagram on the right, where the green circle represents the consultant, helping the two parties to a common goal.
For this type of consulting, the tasks of the consultant are:
Note that if done right, the cost of consulting is always negative: with the help of the consultant, you will actually save cost. Either directly (for example by finding a cheaper solution) or indirectly (for example by saving time, and decreasing TTM - time-to-market -, which increases your profit).
Please see other consulting services below.
B: Management/Business -- A: Development/IT --
B∩C: Business Analysis -- A∩C: IT Architecting