If B1 flips the bat and almost hits an on-deck batter, what action should the umpire take?

In this scenario, when B1 flips the bat and it nearly makes contact with an on-deck batter, the appropriate action for the umpire is to issue a warning to the head coach. This is due to the potential safety risk posed by the bat being flipped in the direction of other players, which could lead to injury. By issuing a warning, the umpire alerts the team about the inappropriate behavior while also promoting the importance of player safety.

This action serves as a preventive measure, allowing the team to understand the seriousness of the situation without escalating it unnecessarily at this point. It also sets a precedent that such actions will not be tolerated, emphasizing safety within the game. In instances where the behavior poses a direct threat, a warning is a common initial response, rather than immediate ejection or other more severe penalties, which might be considered if the behavior were to continue or escalate in subsequent instances.