If a firm is considering investing $100,000 at the end of 2021 for employee training (operating expense). The benefit of the training is to reduce turnover leading to a decrease in operating expenses of $10,000 per year in the future. The firms working capital to revenue ratio is 10% and the firms WACC is 6%. Is it better to analyze this investment decision by considering the incremental after-tax operating profit or the incremental after-tax cash flows generated by this investment? Why?