Despite a lot of repetition and various analogies, some students still struggle to play with proper hand position - curved fingers, thumb on side tip in slide position. As I was reviewing this concept with one of my sons this week a wrestling analogy finally helped it sink in for him. He loves wrestling a whole lot more for him so this explanation really struck a chord for him!
2- Before wrestling its good to do some practice workouts. In piano you can "work out" your fingers by forming finger doughnuts and checking for rounded (not collapsed) knuckles.
3- If you ever get caught flat on the mat... you know you're likely to get pinned unless you can quickly turn and "build your base" (get on your hands and knees and arch or curve your back). In piano flat fingers are a sign of trouble too. Imagine that your thumb is like your coach or referee. Its okay for him to get low on the mat to "check" to see if your other fingers (imaginary wrestlers) are building their base (curved and on tips).