Some managers are above average:
Jay Bowen's stock picking has made the Tampa Firefighters and Police Officers Pension Fund one of the best-performing public pensions in the U.S. As of December 31, Mr. Bowen's annual returns beat pension giant Calpers—which employs 125 consultants and 1,100 money managers—over three-year, five-year and 10-year spans. The Tampa fund appears to be well funded at about 90%. It uses an unusually high annual investment target and discount rate of 10% to calculate the present value of benefits owed to retirees.
The fact that a particular manager has generated above average returns over the past 10 years is not an anomaly, but rather, a statistical certainty. Given Tampa discounts their liabilities by 10%, implying an expected return of 7% or so, I suspect that statistical logic isn't their strong suit, so they simply see this case in isolation, and infer his return based on what looks to them like a long track record, over ten years. As the housing bubble showed, you can't argue against someone who has outperformed over the past 10 years, so I'm sure they are going with their rosy assumption, which I bet will fail with a high probability.
This reminds me of a sales pitch a neighbor broker once told me about. He would take his clients to lunch or dinner, and tell them a long, happy tail about an old client of his firm who had simply put away a modest amount in a company they recommended for over 20 years, and by the time she retired, she had tens of millions of dollars and spent most of her time on charity. This fantasy was very appealing because it really happened, as Home Depot was one of those stocks that went up 100 fold over its lifetime. Further, doling out charity is a great way to enjoy high status in your golden years without guilt: it's something the non-rich simply can't do or criticize.
Of course, for every lady like this, there were thousands who didn't do nearly as well, but only a cynic would conclude such cases were impossible.