The real reason that General Motors ousted its high-energy, former superstar ad director didn’t have much to do with a soccer deal gone awry, which the automaker cited in disclosing the departure to reporters.

Rather, the Detroit Free Press, citing analysts and insiders,reports Joel Ewanick, global vice president for marketing, was forced to resign over his inability to maintain or increase market share under his leadership.

He’s just the latest to go, given the executive revolving door that has marked the giant automaker lately. Ewanick followed 17 marketing executives who changed jobs or left the company, and he’s the fourth in a year.

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“GM’s ‘culture’ — such as it is — was never going to get comfortable with a Joel Ewanick for very long,” the Freepquotes Peter DeLorenzo, creator of the Autoextremist.com blog and a former Detroit advertising director, as saying. “He’s too quick, at times mercurial, and too much a man of motion for the plodding calcification of the GM system.”

The Freep validates the theory that it wasn’t a single bad deed that cost Ewanick his job. Rather, it was a “last straw” scenario:

Ewanick was known as much for the money he didn’t spend as for what he did. In May just before Facebook’s much-hyped initial public offering, GM announced it would stop paying for ads on the social network because the $10 million it spent the previous year didn’t translate to enough vehicle sales.

Days later, he said GM would not advertise during the telecast of the 2013 Super Bowl because the rate of $4 million per 30 seconds that CBS demanded was too expensive.

Partnering with soccer teams was a way to boost Chevrolet’s brand recognition in Europe and Asia, consistent with CEO Dan Akerson’s goal of making it a global brand.

In the U.S., GM’s marketing strategy has yielded mixed results. Internal discussions over the success of the tagline “Chevy Runs Deep” have not resulted in any change yet.

Ewanick launched a “Love It or Return It” program earlier this month that allowed Chevrolet buyers to return their vehicles between now and Labor Day if they are not satisfied and if they have driven the vehicle less than 4,000 miles. Chevrolet also has adopted comedian-actor Tim Allen as its advertising voice.

Some analysts say all GM brands will do better in the next 18 months as crucial new models come to market. Those include the 2013 Chevrolet Malibu, the Cadillac XTS and ATS and all-new Chevrolet and GMC pickups reaching showrooms late next year.