Recently, Yum China announced its first-quarter financial results. The data showed that the company's same-store sales rose 3 percent year-on-year, operating profit rose 33 percent year-on-year to $395 million, and net income rose 41 percent year-on-year to $288 million.

Meanwhile, Yum China will continue to open stores at a high rate this year, with plans to open 600 to 650 new restaurants, and will continue to sink into small and medium-sized cities.

Also in the first quarter of this year, Yum China's online takeout business increased to 16 percent of the company's sales, with more than 3,300 KFC and 2,100 Pizza Hut restaurants in 970 cities nationwide offering the service.

Simply put, Pizza Hut sales fell, but KFC went way up, offsetting the losses Pizza Hut inflicted on Yum, and the broader market remained up. This isn't the first time Pizza Hut has held KFC back; Pizza Hut sales also did poorly last year.

And throughout 2016, Pizza Hut's earnings declined sequentially, while in contrast, KFC was up 3 percent. Why the same Yum division, between the two giants dragged back always Pizza Hut?

In 2014, Yum's third-quarter report showed that Yum's total sales revenue in China slipped 9.5% to $1.84 billion, and operating profit plunged 40% to $202 million.

And after 2012, China's restaurant market exploded with new brands and new dishes. The market's impact on foreign fast food like McCann's went through the roof.