The problem at Yahoo starts with the board of directors, which has appointed 5 CEO's in six years. This indicates that board members are not unified on the direction they want the company to go. Appointing new CEO's get some sizzle and interest, but only cash flow sustains a share price.
And, as I read this board, the bulls seem to be arguing broadly among themselves. Divesting non-strategic profitable units is all well and good, but how is that capital going to be deployed? This is a big and complex question, but when I buy Valero or JnJ or Google or Adobe....I get a company that KNOWS where it is going. Yahoo seems to have a rather rich valuation for a company which does not have a committed and tested strategic way forward.