When I'm tracking my athletes, if I am not seeing improvement, it means something has to change, but the cause needs to be determined. There are usually 3 potential causes:
1. Need more recovery, workouts have been too big of a load, or recovery needs to be enhanced/addressed
2. Need more training, training hasn't been consistent
3. The training stress the athlete is under they have plateaued in their response to, time to do something different
Coach and athlete share some responsibility in each of these, but the important thing is that both recognize and understand which one is the cause, and how to proceed with training if there is a plateau in performance.