One of the classic strategies against an opponent from time immemorial within the FGC was to look at what their hands were doing. This was a strategy that enabled the opponent to have an idea of what the opponent was trying to do.
Interestingly, this is a practice that has continued into modern times and even on the biggest stages.
Evo 2023 has offered up quite a few sights, but one of the more amusing ones was the sight of Evo Champion for KoF XV, Xiaohai, hiding his controller from the view of his opponents. Xiaohai had already drawn a lot of attention for using the Qanba Obsidian 2 Gold Edition, which as the name implies, is a golden fight stick.
However, he garnered even more attention for covering up his controller with a large box whenever he had to play.
Furthermore, the box was reportedly provided by his sponsor, Qanba.
Xiaohai is not by any means the only player who does this, as this practice exists to protect players from having their moves telegraphed.