Now that's a weird comparison, but hold on a minute.
When a person says they want to train really hard, but hardly ever show up, they become a weed.
Giving a half-hearted effort or simply being absent most of the training week (without clearly communicating to their coach ahead of time) makes their coach start to lose interest in them.
When that happens, they may get a one-on-one talk from the coach or he might just cut them from the program right away.
Either the weeds are choosing to fade out of the picture.
Going, going, gone :(
Lesson: Don't be a weed!