Samsung Electronics, maker of the popular Galaxy smartphones, has just announced it’s new head of mobile design, Lee Min-hyouk, giving previous head, Chang Dong-hoon reigns on head of design strategy team, which focuses on the long-term design strategy over the entirety of the company, devices, and appliances. This announcement was made amid the heavy criticism of the Galaxy S5.

At 42, Lee became Samsung’s youngest senior executive in 2010, thanks to his work on the Galaxy series. Before becoming the mobile design head, Lee was the vice president for mobile design. Because of his work, the Galaxy series took off and has been dominating the smartphone market since then, selling twice as many smartphones as Apple.

Chang said that his team was responsible for the Galaxy S4, including the phone’s technology that tracks a user’s eye movement. He has also been involved with other Samsung Galaxy smartphones and the Galaxy Notes. Despite Chang’s shift in occupation, he will still have some involvement, overseeing the overall design strategy for all of Samsung’s businesses, which will include mobile communications.

With so much weight on Samsung’s product design, why was Chang swapped for Lee? The Galaxy S5 was released with sales that surpassed their predecessors, according to the company, but the smartphone has received mixed reviews since its launch. The S5’s all-plastic design and lack of hardware innovation has received a majority of the criticism.

Lee was credited with the Galaxy design, which might explain why they opted for someone who was responsible for so much of the Galaxy’s success.

This isn’t the first time that Samsung has made a critical change in staff. The company is also known for switching up its executives. This particular change could be a result of slowing mobile sales, Samsung’s biggest source of profit. The change comes at a very active point in Samsung’s sales. Only days before the announcement, the GS5 Developer Edition arrived at Verizon. Samsung has also begun to release its next iteration in the Knox security suite for its smartphones.

Samsung’s first quarter earnings in the smartphone margin have remained the same since this time last year, due to rising components costs and uncertain S5 sales. The company has also been in a very public battle with Apple over patent litigations. Apple claims that Samsung has been copying Apple’s design.

Despite Lee, a hopeful for Galaxy’s future, and his control over Samsung’s mobile designs, the company’s co-chief executive, J.K. Shin, will still have the final say in the design.