Pre and post chat are considered during tribunal from reports.
I thought I would post this in case others are asking this question..."is the pre and post chat looked when reporting a player?" Well, I wrote [riot] during this particularly nasty pre game that i SS and asked this question when I had their attention. Here is their response.
Legendary (Riot Games Player Support)
May 2, 13:52 [2016]
Greetings player,
Our systems do have full visibility on the behavior of players in the pre & post game lobbies and reports made after games do help bring
these types of players to our attention for potential punishments.
Legendary
Player Behavior & Game Support
Jarvan IV Jungle
"For the King!"
I originally wrote Blizzard, meant to say riot. Thanks for providing feedback guys.