Many dogs will brush an edge or point ball on the initial send to the ball formation. This often results in a ball being 'dislodged' and a possible penalty.  The video shows methods to help the dog learn to stop a short distance behind the point ball

As the ball formation gets larger and further away, some dogs like to stop 'at the corners" rather than going all the way out initially to the Point Ball.  Unless they actually dislodge one of these balls, it is just time, but it is best to teach them to go all the way out on those initial sends.

In Jan 2020, NATE had a comprehensive Clubhouse Chat specifically on this topic.  The adjacent video is recommended viewing.

Do you have a ball biter? Here are a few suggestions from member Carolyn Bigley.

1. Try raising the ball up on a chair at dogs eye level and reward only nose pushes.

2. Make sure you are using the correct ball size

3. Have your dog nose pushing multiple objects so that they start generalize the nose only "push" command.

Once your dog really understands that "push" means nose only, you can have them start moving the ball short distances working your way up. You may even have have to begin with another word, such as "drive" if your dog already associates "push" with rolling the ball and biting.

Other dogs, cars, people, and squirrels just to name a few can challenge even the best dog's focus on a Pop-Up field (& to a lesser extant on a Trial field).  Below are some strategies to keep your dog's attention on you and the game.  

In essence, this issue is an extension of Impulse Control (see above).  Some of the solutions for Impulse control will also help with maintaining your dog's focus on you and the task at hand.

The key to take your dog to as many new places and situations as  possible.  And while there, ask for performances of solid behaviors (sit, down, spin, etc.).  Use liberal amounts
of rewards (food, toy, praise) when the dog is calm and focused on you in the situation.

From Carolyn Bigley:  NATE Training Resources Tip of the Week- Getting your Dog’s Focus ( Foundation Exercise)

Getting you dog’s full attention is an important part of training. Teaching the “Look” or “Watch me” is used when you need your dog to pay close attention to you, even when there are distractions. It is especially helpful for those who participate in dog sports and work as a team. Teaching your dog to focus makes it much easier to communicate and makes it easier for them to follow your instructions.

Monica Pielage demonstrates Carolyn's advice by shaping eye contact first at home to teach the behavior and then in the second video practices in a distracting environment.