The 12-page report was intended to save soccer’s governing body, FIFA, in its moment of existential crisis.

Filled with reform proposals and drawn up by more than a dozen soccer insiders in December 2015, the report was FIFA’s best chance to show business partners, U.S. investigators and billions of fans that it could be trusted again after one of the biggest corruption scandals in sports history.

In bullet points and numbered sections, the report championed high-minded ideas like accountability and humility. It also proposed concrete and, for FIFA, revolutionary changes: transparency in how major decisions were reached; term limits for top leaders and new limits on presidential power; and the abolition of well-funded committees widely viewed as a system of institutional graft.

And there on the report’s final page, deep down a list of its authors, was the name of the man positioning himself as FIFA’s savior: Gianni Infantino.

Mr. Infantino, an administrator at European soccer’s governing body, had been enlisted to help sketch out the overhauls. By the time they were announced, he was a candidate for FIFA president. Presenting himself as a clean break from the past, he swept into office a few months later and quickly began enacting many of the changes. The sport’s six regional confederations promised to clean up their acts, too.