Understand the current process
Building a model forces you to ask questions and tie together information not previously understood. In addition, modeling shows the critical timings needed to make a process perform. Finally, understanding how things work allows for formulating solutions that will solve the actual problem.
Accurately predict how changes perform
Simulation is a clear winner of all methodologies used to predict the impact of process change. Compare alternatives side by side by implementing any changes in the model first. No other technology allows accurate prediction of future performance from process changes.
Show people why the current process performs as designed. Then, allow others to participate in the process and see why specific changes work and others don’t. When they see why things work, they will jump on board and support the best solution.