I think that describes it very well if you are between arm's reach and kicking distance from Sensei. However, if you're within arm's reach, a more apt description is your arm is already caught in a meat-grinder. You just know it yet. With the shark, you need only avoid his mouth. With Sensei, it's like trying to evade all of the tentacles of an octopus. Nobody can do it. In order to have any hope of success at attacking Sensei, you would have to have truly swift, powerful jabs and move in and out swiftly, attacking his ribcage, not his head, without crossing your legs and keeping your weight off of your front leg, because Sensei is going to kick or sweep that leg. He has had too much practice for you to be able to strike his head. It's much easier to attack the torso than the head, but you have to have really destructive power, or he'll get you even after you have struck him.