If you think leadership doesn’t matter, look at Boeing.

Last week, following the second fatal crash of one of its new 737 Max 8s in less than six months, Boeing Co. shares plummeted by 12 percent, destroying more than $28 billion in shareholder value. It was Boeing’s biggest loss since September 2001, when terrorists flew four of the company’s planes into the World Trade Center and Pentagon. In the dark days that followed, Boeing’s stock price fell to less than $28 a share from a monthly high of almost $52 as half its orders for new planes were canceled or delayed.

But over the next five years, Boeing’s Commercial Airplanes Group soared back to record sales, revenue and earnings under the leadership of its new CEO Alan Mulally.

Mulally, who had led the development of the Boeing 777 — the company’s most profitable aircraft ever — was tapped to lead the group just a few months before the terrorist attacks. His unshakeable...