And another one bites the dust

This weekend, Joel Ewanick quickly and quietly resigned from GM as its global CMO.

It was an unexpected and unceremonious end for Mr. Ewanick who came in guns a-blazing just two years ago, one month after he accepted the CMO position at Nissan.

Why has he been let go? Rumors are rampant that it's tied to both the flap with Facebook and his recent multi-million dollar deals for Chevrolet with both the Liverpool and Manchester United football clubs.

While those decisions may have accelerated this action, it boils down to one thing: GM sales have been underperforming the market during his tenure.

For the first half of this year GMs sales are up just 4% while the US market is up 15% – with Ford, Honda, Toyota, Nissan, Hyundai, Chrysler, VW and Kia all showing larger gains.

Is it all his fault?

Probably not. He walked into the GM when its brand perception was at its absolute nadir. The product roadmap he inherited was already in place – so he had little or no input on the Cruze, Volt, Verano, Malibu, Regal, ATS, etc. While all are solid products, none with perhaps the exception of the Volt and ATS, are world-beaters. And in the automotive category, nothing's more important than the product.

Still, little of the work created during his tenure has been particularly memorable. Chevy Runs Deep is a weak tagline for an iconic brand. The Cadillac ATS launch campaign doesn't do a great job of differentiating it from BMW or Audi. GM also lost the buzz coming out of the Superbowl to Chrysler (a company with fewer resources and inferior products) both years under his watch.

CMOs, like head coaches in the NFL, are hired to be fired, with the average CMO lasting just 30 months in his or her job.

Mr. Ewanick was never afraid to make bold moves – hiring Goodby without a review, dropping Facebook ads, forcing IPG and Omnicom into a joint venture, etc. Bold works when the numbers follow. But when they don't, it's like standing up in a fox hole.

You won't survive very long.