A brand new pitcher at 10U rec, IMO, should be concerned with getting a straight fastball with a lot of consistency. A change-up and spots after that. Baby steps though. I'm also not a fan of experimenting during a game. Throw what you know. A pitcher at that level owes it to their defense to get the ball in play. A walk-fest is no good for anyone. Not the pitcher, not the defense, and not the other team who is trying to learn to hit.