Good questions. I don't know.
1. Cancelling yourself after you have been accepted should decrease reliability imo.
2. Being late to a battle should also decrease reliability BUT not more than it would if you left a battle a bit before the end.
3. It doesn't make sense to get a penelty if you first get accepted and then get removed though.
It would make sense if you got decreased reliability for disconnecting and connecting.
But most importantly should be the total time played, for example:
- If you play 29 minutes of a 30 minute long battle it's good.
- If you play 20 minutes of a 30 minute battle it's bad.
- If you play 10 minutes of a 30 minute battle it's really bad, unless your contribution (many kills & few deaths) make up for it.