Ya it really depends on what the ban was for. To go into detail of what BlueThingamajig posted:
3rd Party Programs: They obviously wouldnt release details as to how they know or else the people actually working on these programs can improve to be less detected from Riot. I mean it would be hard to say who truthfully didnt know, and someone who is looking for an upper hand.
Behavioral/Toxic ban are pretty straight forward as they give you your most recent chatlog games usually 3 logs.
Account Sharing/MMR Boosting Im sure are worked to find where the account is located. If you mainly play in California then 30mins later end up being logged in New York, something would be up. Plus im sure it takes into account of how the person is playing. If you play say Yasuo getting no kills, less than 100 CS, numerous amounts of death. Then all of a sudden your next couple of games you are getting 20+ kills, loads of CS, little to no deaths. it would bring up a red flag since it would seem like someone else is playing on that account.
I mean it is hard to actually provide evidence especially in terms of the 3rd party program bans as well as account sharing. You dont want to give the information to the wrong people, because once they get their hands on it you know the next attack will go with full force. How would you feel if every single game has someone hacking, scripting, etc.
