2. Check swing.

If it is the plate umpire's judgement that the batter made an attempt to swing at the ball (but not a full swing), the plate umpire shall call the pitched ball a strike. This call is NOT to be appealed to the base umpire - use the guiding principle that the plate umpire does not call it a strike unless he/she saw the attempted swing - therefore no need for an appeal of what the plate umpire saw.

However, if the batter attempted to swing at the ball but the plate umpire did not see the attempt (perhaps blocked out by the catcher) then a ball shall be called. With this call, the plate umpire does have the opportunity to check with his/her base umpire(s) with or without a request from the defensive team. The plate umpire may make the request on their own or may choose to make the request when requested to do so by the defensive team. The key to the base umpire is that they shall only answer a check swing request made by the plate umpire - they do not respond to a request made directly to them by a defensive player.

Should the base umpire see the attempt that the plate umpire did not see, they shall respond by calling "yes" and the call shall be changed from ball to strike.