I have been playing for three months now and just read this guide. It confirmed a lot of what I observed already, nice job. But being a Mathematician I have to disagree with your odds for a crystal team running into a hero. You need to take into account that the defending team may have one, two our three groups. The odds of running into a hero in this case is 4 out of 7 or ~57%. If anyone wishes I can explain in another post.
For those of you who have only one or two legend heroes like me, this guide will still work for you. Just substitute in what heroes you do have. It will help if you multiply the heroes damage with it's attack rate to get a damage rate. The damage rate can be used for accessing how good the hero will be for a crystal team. The heroes attributes can be used as a tie breaker for close calls.