When Bill Gross left Pacific Investment Management Co. in 2014, it wasn’t surprising that investors bolted. But now customers are deserting another Pimco star manager who’s still in his seat. Investors last year pulled a combined $15.8 billion from two mutual funds run by 61-year-old Rob Arnott -- Pimco All Asset and All Asset All Authority-- as their returns trailed most peers for the third straight year. They had Pimco’s most...