I think for tall players, they often give the impression they lumber around, having no speed at all. In reality, many move as good as smaller guys. Just a trick our own eyes play us, or the camera, I don't know. I remember this ice hockey player Mario Lemieux, often talked as the heir of Wayne Gretzky. Most fans think of him as slow, but the players themselves admitted they got fooled many times when Mario just zoomed by them with a lightning first step. Perhaps Raonic is not so slow as many tend to think.