What?
He's 1.68m which isn't tall, but it's not exactly small. It's basically the same height as both Xavi and Iniesta (1.70 m)
Gio is a midget. 1.62m. He's also a forward which means he has to compete with big physical defenders.
Much easier to play in midfield as a shorter player, slighter player, where you are not expected to battle physically with big defenders.