In the years following Steve Jobs’ death in 2011, a power struggle emerged within Apple over the future of the MacBook product line. According to a high-level source well-versed on Apple’s products who spoke to veteran journalist Walt Mossberg, this struggle pitted the company’s vaunted design team against its engineering and product management staff.

At the center of it all was Jony Ive, the legendary head of Apple’s design team who had a uniquely close working relationship with Jobs. With Jobs gone, Ive was given even more control over product development by new CEO Tim Cook, who did not involve himself in product details the way Jobs meticulously did. “Tim is a guy who knows what he doesn’t know. He knew he wasn’t a product guy,” Mossberg explained. “Steve Jobs was his editor. Steve Jobs would pull him away from his crazier instincts.”

Without Jobs acting as his editor, Ive soon came to believe that Apple no longer needed two separate MacBook lines—the mass-market MacBook Air and the high-end MacBook Pro. Ive decided Apple could build a single MacBook model that would blend the ultra-slim form factor of the Air with the power of the Pro. This unified MacBook would sport an ultra-thin, lightweight chassis akin to the Air but pack a powerful punch under the hood. It would also command a premium price, boosting Apple’s profit margins.

Ive’s proposal was baffling to Apple’s engineering staff, who considered the MacBook Air their most successful product ever—a lightweight, entry-level laptop that served as a gateway into the Apple ecosystem for millions of consumers. They had no desire to abandon that massive base of Air customers or the Air concept. What they wanted was simply to keep iterating on the MacBook Air with new upgrades and refinements each year.

For the next couple of years, Ive and the design faithful squared off against the engineering and product teams. It was an epic battle for the soul of the MacBook. Ultimately, Mossberg reports, the engineers managed to beat back Ive’s vision for a unified MacBook line. Instead, Apple released a lightly updated version of the MacBook Air to keep customers satisfied. But the tug-of-war exposed a new power vacuum and lack of alignment in Apple’s ranks resulting from the absence of Steve Jobs, the master product editor who had always kept unruly egos like Ive’s in check.