A wide angle lense would have been much better and the focus isn’t great… hard to time as I was lying on my back and couldn’t see when he was coming…
It’s a great idea, but as you said the focus is poor and the shot suffers from being just too soft. In terms of focus and timing you could try trap focusing. I’m not sure how to do it on Canon’s but you can prefocus your camera to a particular distance, choosing the aperture you need for what ever depth of field you want. The put your camera into trap focus. When ever an object comes into focus (at the prefocused distance) the camera will fire off a shot. I’ve used it once or twice, just playing with the functionality and it would work great here! Another suggestion would be to use flash, it would help freeze motion, give a sharper result and also really lift the shadows.