PIMCO Total Return Outflows Top $64B: Morningstar

These issues played a part in outflows at the time "with Mohamed leaving the firm and Goss making statements that gave the impression of poor communication and led some people to question leadership," Rawson noted.

"But investors embraced them after the financial crisis," the analysis said.

Given that U.S. outflows from the Total Return Fund have reached an estimated $64.1 billion, the atmosphere at the firm is likely to be grim.

"This must be causing tension in the firm as assets have shrunk a significant amount," said Rawson. Bonuses paid to employees and management are tied to asset flows, "and those working in the industry are not used to losing assets."

"There's been a lot of shuffling of the ranks at PIMCO, and as assets shrink, the bonuses levels should be negatively impacted," the analyst stressed.

("Patient investors are rewarded over the long term by sticking with core bond allocations in a diversified portfolio. The PIMCO Total Return fund has outperformed its benchmark and a majority of its peers over the last 1, 3, 5, 10 and 15 years," the company said in a statement given to Dow Jones.)

The situation at PIMCO stands in stark contrast to that of rival bond shop DoubleLine, led by Jeffrey Gundlach.

Morningstar's estimates that the net inflows for the DoubleLine Total Return Fund in June were $515 million. Total assets in the fund at the end of June were $33 billion. 

"This is representative of the [medium-term] category overall," Rawson said. Its popularity with investors has improved, since "the interest-rate environment is less dire than a year ago when they were concerned with a sharp rise in rates."