• Bridgewater rigged its "believability weighting" system to keep founder Ray Dalio on top, a new book says.

• The system signaled how much weight someone's opinion carried and was theoretically meant to help identify talent.

• After two underlings outranked him, Dalio was set as the baseline for believability, per "The Fund."

A new book said Ray Dalio was less than thrilled that other employees were scoring higher than him on Bridgewater's famous "believability weighting" scale, and that the hedge fund subsequently rigged the system to ensure his place at the top.

That's according to "The Fund: Ray Dalio, Bridgewater Associates, and the Unraveling of a Wall Street Legend," out Tuesday from New York Times finance reporter Rob Copeland.

Dalio brought on a consultant in 2009 as an advisor to Bridgewater's management committee and tasked him with creating a system for ranking employees, the book said. Dalio's idea was to have something like a baseball card for each employee — visible to everyone and ranking them on dozens of different attributes in an attempt to spell out their strengths and weaknesses, the book said.

Categories included things like determination, practical thinking, and visualization, according to the book, but one metric — believability, which was a combination of all of the ratings in each category — trumped them all. Bridgewater's believability weighting system, in theory, was supposed to help determine how much weight a person's opinion carried and to help identify hidden talent within the firm.

The consultant pushed back against the idea of mixing all of the ratings, the book said. According to the book, he told Dalio: "You can't average the numbers there … that's like taking your shoe size, adding it to your body temperature, and adding it to the time of day, and then dividing by three, and having it to the third decimal point, and thinking you have discovered something."

Dalio reportedly responded: "Believability cascades. You should have done this. I just did your job for you."

Bridgewater started experimenting with Dalio's believability weighting system with a prototype allowing staff to see each others' scores on a scale of 1-to-10, but Dalio wasn't pleased, the book said.

He'd recently been told two people at his hedge fund — one in investment research and the other in IT — were scoring higher on believability than he was, according to the book. On a phone call to the consultant, Dalio asked, "Why doesn't believability cascade?" the book said.