My dear, I think it has to do with the composition of the team you joined, the teams that applied alongside yours, the Steemit team's perception about you and your team at the time of selection, and other factors. But consistency in application, joining different users on different periods. Doing exceptional work on the blog like being visible in terms of publications, comments, support to other users and the like. I don't really understand the criteria but all I know is that with time, you might be a winner. What I mean is that you might be lucky to be selected if you don't give up. But then even if you are not selected, it doesn't necessarily mean that you had done anything bad, it might just be that you weren't lucky. Besides, the number of teams to be selected are limited and those that usually applies are much. Be patient, keep trying your best and keep supporting those that have been selected, someday, yes, someday it might be you. Don't give up easily!