Inherent problem
1)This way of working is good if only the customer do not know anything much about the project or do not have mch IT knowledge and he/she only provide the requirements.
2)This way of working will waste manpower as well because one individual might have better knowledge on one scope of the project and do not have too much knowledge on the other, this will reduce his efficiency.
Evolutionary team structure
1)It give a rough guide of how much time and effort is to be spent on each individual jobscope at different stages of the project development.
2)One good advantage of the evolutionary team structure is that everything is going on at the same time although the focus varies at different stage of the project developmant.
Suggestion on improvement
At every stage of the project development, i would suggest allocating 10% of the time and effort at getting the customer response and feedback. Despite the customer having very minimum IT knowledge , it is always good to ask them for their opinion as after all they are the ones paying.