So I don’t think being a non-starter on a mainstream varsity team is a “bad” EC, and in fact it sort of speaks for itself as a major contribution to the school community in a way which is handy. But I do agree the activity description could include team success (if any), and also a brief description of those summer activities.
Then if the applicant wants “more than normal” credit for being on varsity (which I again think gets significant credit to begin with), probably that will have to be raised in an essay, or maybe a recommendation.