CalPERS is shifting its internal approach to measuring investment success by adopting a "total portfolio benchmark." This approach has pros/cons, but what shouldn't be lost is that CalPERS has always had a single benchmark it should hit—the assumed rate of return.
There is value in having a benchmark for investment performance relative to peers, or relative to what was possible in the market. In practice, though, many public plan investment benchmarks are soft targets that can be gamed by investment managers. Plus the heavy media attention on portfolio benchmarks often obscures the most important target— what actuaries assumed returns would be when calculating contribution rates.
Public plans aren't the same as other institutional investors when it comes to how we should think about their success. Beating the market, or beating other investment managers doesn't always mean a pension fund is appropriately funded. And when investments underperform the assumed return, the price is paid for by taxpayers (higher govt employer contributions) and public employees (higher member contributions, lower pay, or both).