Its very important that you understand its not possible for the contest holders to leave feedback for every designer who participates in their contests. So if they do not like your design or are not interested in, they will eliminate your design.
If they like your design and want to continue working with you, then they will give you feedback in form of stars and comments.
Getting eliminated is not the best feeling, but it also does not mean that your design was bad. Maybe its not something what client is looking for.
Note: Clients can ban you from submitting any designs in their contest if they feel you are spamming or submitting designs with minor changes or almost no changes. So please do not engage into such activities.