Tim Cook timed his exit so John Ternus would open his tenure with the iPhone Duo

A month into his new title, Tim Cook sat in Apple's U.K. headquarters in the Battersea Power Station and told The Independent's David Phelan why he gave up the CEO job when he did ^[9][10]. "I wanted John to have some wind at his back," Cook said. "And the wind at Apple is very much based on the product cycle." ^[4]

The date was chosen on purpose. According to 9to5Mac, Cook said the Duo launch at the start of Ternus's tenure was fully planned ^[7], and MacRumors reported the momentum was part of his reason ^[3]. Ternus became CEO on September 1 and unveiled the phone on September 9 ^[1][11]. Cook said the handover "actually started years ago" and that the aim was "a textbook example that people could look back to and learn from" ^[5].

Ternus got the attention: the first public moment of a tenure, with a new phone attached. The result has not come in yet. In the same interview Cook said, "The Duo is coming in a few weeks and it's amazing." ^[4] By his account, the phone behind the tailwind was still weeks from buyers when he spoke. The published accounts of the interview do not include preorder or sales figures.

Inside a company, an unveiling feels like momentum. Cook said, "This product cycle feels unbelievably great." ^[4] Buyers give their verdict later, when they decide whether to keep the phone past the return window and what to buy next. Those results will come in while Ternus is CEO.

Some of the credit is his own. Ternus ran Apple's hardware engineering before he ran the company ^[1]. I'd expect the group he led to have done much of the work on a new iPhone.

Cook has his own separate job. Apart from his relationship with Ternus, he said, "what I'm focused on right now is worldwide policy." He added, "I'm not meddling. I'm not a meddler." ^[2] His advice to Ternus was "make it your own job" and "don't mimic me. Just like I didn't mimic Steve." ^[6] Jobs had once told Cook not to make a decision just because Jobs would have made it ^[8]. Ternus has since told staff, "I need to spend my time where I can add the most value for Apple," Bloomberg reported, according to The Verge ^[12].

Anyone planning a handoff of their own can sort the choice on two axes. One is whether the next big release was mostly built before the handoff or after it. The other is whether the outgoing leader stays on in a separate role or leaves. Apple picked a release built before the handoff, with the outgoing leader staying on ^[1][2]. That combination gives the successor visible momentum and an adviser who is still in the building. The cost is that the first hard numbers, such as returns and upgrade rates, judge decisions made before the new person took over. I would time a handoff to a launch only when the successor helped build what is being launched, as Ternus's hardware background suggests he did. The test is who holds the job when the release's first retention data comes in, and whether that person made the calls the data will judge.