Many large cap stocks trade at reasonable prices compared to cash flow and earnings. The problem is that the economy is slowing and it is very difficult to forecast how slow the economy will eventually get and what effect that will have on earnings.
Reported earnings are backward looking and forecasts are always way off at economic turning points. In 2007 nearly $100 in S&P 500 earnings was being forecast for 2008. Reported earnings for 2008 ended up being negative. I don't believe that will happen again but I do believe that forecasts could be way off if the economy continues to deteriorate.
There is also the possibility of a tail event due to numerous global imbalances and a slowing global economy. Valuations are not at a point where one does not have to worry about the economy and until we get to that point everything is a trade.