It's wrong to strike a little kid.
Grant is coaching a youth baseball team, and they are performing poorly at practice.
Grant wants to motivate his team to play better.
Grant comes up with an encouraging speech for his players and offers them a reward if they can meet a goal.
Grant smacks one of the kids on the head, insinuating that he will do it to others if they don't pick up their play.
The kids start to play better and are able to earn the promised reward.
The kids tell their parents, and many of them are pulled from the team.