Not enough Barbie dolls were sold during the holiday season, but it's not CEO Bryan Stockton's problem anymore. After struggling to attain growth at Barbie's parent company, Mattel, Stockton is stepping down effective immediately. He's being replaced by Christopher Sinclair, a 64 year old who has served on Mattel's Board of Directors since 1996.

"Mattel is an exceptional company with a great future but the Board believes that it is the right time for new leadership to maximize its potential," said Mr. Sinclair, in a statement released by the toy maker.

"We will be working during the coming months to revitalize the business and to identify the right leadership for Mattel as it enters its next phase of growth and value creation", he said, promising expanded product innovation and improved retail execution.

Under Stockton, sales slumped for the last five quarters. Why is Mattel struggling? Its flagship doll, Barbie, is not as relevant as it was in the past. This past holiday season, Barbie was dethroned by Walt Disney's "Frozen" dolls as top Toys for girls, according to the National Retail Federation's holiday "Top Toys" survey. It was unprecedented in the 11 years of the survey.

Barbie, who's full name is Barbara Millicent Roberts, has also been the target of criticism because of its portrayed ideal of beauty: large bust, tiny waist, and very unrealistic proportions.

In the last couple of years, the iconic doll faced the competition of Monster High dolls - also made by Mattel - as girls are shifting towards more modern concepts. On a global scale, and battling fierce competition from Lego, Mattel also acquired MEGA brands, the maker of Mega Blocks (a Lego rival) in 2014.

Shares of Mattel dropped as much as 6.54% on Monday, following the announcement of the new CEO and the release of preliminary fourth quarter and full year 2014 financial results.

It wasn't pretty: Mattel reported net sales of $1.99 billion, down 6% from last year. Net income fell 59% to $149.9 million, from $369.2 million in the fourth quarter of 2013. Operating income for the quarter was $237 million, compared to $479.3 million in the previous year.

Although the results are still preliminary, it's a gloomy situation for the El Segundo company.

Net income for the full fiscal year was almost cut in half, decreasing to $498.9 million, as sales fell 7% to $6.02 billion. Mattel is nevertheless paying a cash dividend of $0.38 per share to its stockholders, payable on March 6, 2015.

"On behalf of the Board and everyone at Mattel, I sincerely thank Bryan for his many valuable contributions over the past 15 years in expanding our business and portfolio of brands and building our executive team", the new CEO said. Sinclair, who was once PepsiCo CEO, will oversee the ongoing strategy to diversify Mattel's offerings, as well as the effort to come up with more modern interpretations of the Barbie doll. The company will be showing off the new ideas next month, 14-17 February, at the New York Toy Fair.