In his commencement address in May at the Virginia Military Institute, former U.S. Secretary of State Rex Tillerson railed against his former boss . “When we as a people, a free people, go wobbly on the truth, even on what may seem the most trivial matters,” he inveighed, “we go wobbly on America.” The breakdown in Tillerson’s relationship with Trump was an inglorious turnabout from the chorus of optimism business leaders voiced during Tillerson’s nomination to the nation’s top diplomatic post, in December 2016.

But looking back on his short, and by most accounts unsuccessful, tenure at the State Department, it may be time for every corporate executive to re-examine the leadership model for which Tillerson was so highly praised less than two years ago.

High hopes, low scores

In the lead-up to Trump’s inauguration, Jeff Immelt, former CEO of General Electric, praised Tillerson’s “exceptional understanding of our country’s essential and strategic role in the world” alongside his negotiation skills–abilities Immelt believed Tillerson had honed in his decade as CEO of ExxonMobil. Former Medtronic CEO Bill George, a former Exxon board member, similarly believed that Tillerson’s experience with foreign leaders would help him as secretary of state. And Tesla CEO Elon Musk thought Tillerson would prove to be “excellent” in the role, given that he “obviously did a competent job running Exxon.”

It wasn’t strictly business leaders who felt this way; influential foreign-policy experts voiced a similar logic. Former secretary of state James Baker, who has business ties to Exxon, maintained, “As CEO of one of the world’s largest and best-run companies, [Tillerson] has demonstrated the management and negotiating skills, and has the international experience, that are required in the job.” (It’s no accident, of course, that these were many of the same abilities Trump himself touted on the campaign trail about himself. In nominating Tillerson, the president may have fancied himself selecting a leader whose experience and reputation he could relate to.)

Unfortunately, Tillerson failed to meet those expectations in ways that challenge the very belief that largely propelled Trump into office–which, after all, had been popular long before Mitt Romney banked his own 2012 presidential campaign on it–that business leaders naturally have what it takes to become good political leaders.

Immelt’s confidence in Tillerson’s grasp of the role that the U.S. plays in global affairs wasn’t exactly rewarded. Last May, Tillerson gave a talk to State Department staff describing American values–namely, “freedom, human dignity, the way people are treated”–as potential “obstacles” that shouldn’t necessarily override strategic foreign-policy objectives, like achieving security and prosperity for Americans. In response, Tom Malinowski, former assistant secretary of state for democracy, human rights, and labor, described Tillerson as “clueless about what the world expects of America, including that we defend universal values and norms.”

As for leveraging his established relationships to bring foreign leaders to the negotiating table, Tillerson again came up short. It’s one thing to negotiate an oil deal with Russian oligarchs and another to negotiate the withdrawal of Russian forces from Ukraine with Kremlin and United Nations authorities. Despite many months of pressure, Tillerson failed to make a dent in that issue; just last week, the U.S.’s U.N. ambassador Nikki Haley was still pleading the case, which earned a dismissive response from Russian officials. Outside the usual diplomatic toolkit, including sanctions, Tillerson certainly didn’t get a chance to show off additional chops as a negotiator, not least (yet not solely) because his efforts were repeatedly undermined by his own administration–an internal management issue that Tillerson was likewise unable to resolve.