The exact moment of any corporate turnaround is almost impossible to pinpoint. But if Sony's latest numbers truly do signal the revival of the Japanese icon — the company just posted its best quarterly profit in seven years — then the transformation may have begun last April, when Kenichiro Yoshida was promoted to chief financial officer.

It's probably best not to get too carried away by today's numbers, which prompted an 18 percent surge in Sony stock. If I had ¥100 for every time an analyst declared the tech giant was "back" over the past 15 years, I'd be retiring early. But bullish projections of a $171 million operating profit for the year suggest there's a chance posterity may one day view Yoshida and Sony CEO Kazuo Hirai as the tag team that resurrected one of Japan's most fabled names.

How have they done it? While Hirai smartly boosted investments in the company's unglamorous chip unit to build more modules for phones, tablet computers and automobiles, Yoshida began the hard work of cutting off a number of dead limbs within the sprawling company.