"Talking your book" == putting money where your mouth is. Bill Gross, especially when he was at PIMCO running the world's largest bond fund, had to invest in what he believed in. They couldn't market themselves out of a losing position.
If it was positive NPV for them to keep quiet, every investor would.
CNBC and Bloomberg TV are full of talking heads all day long, though they only scratch the surface on potential fund managers.