A PieceAnimator, or proxy, steps in for the current piece, allowing the key interactors to only reference and command one piece that represents the piece that is falling down the screen at any given time instead of referencing each and every piece that is created on the board.

The proxy's reference to "current piece" is constantly being updated each time a piece instructs its squares to stop and to add themselves to the board at their current positions.

reference: current Piece