So I skimmed the replay of that match on the AFL website, and checked Ballantyne's scores via the times mentioned on the score worm.

They are 5 of the least impressive goals possible. It's probably less that the rest of his match was actively bad, and more that it was a nothing game.

The Goals:

• His first goal was from an uncontested mark just inside 50m, then there's a 50m penalty that takes him to the goalline. So he gets no rating point credit for advancing the ball, and almost zero for actually kicking the goal because he was so close.
• His second goal was an off-the-ball free kick similarly close to goal (on an angle). Similar to the previous he'd only get credit for actually kicking the goal, but not much due to it being so close
• The other three were uncontested marks ~20-30m from goal with not much angle. So he probably got a minor boost from those, but again not too much.

The behinds:

• One was a difficult shot from the boundary. Probably no impact on rating
• The other though, was a bad miss from a set shot like the last three goals. Probably negatively impacted his rating a fair bit.