May 2019 - last edited May 2019
I have been champion many times. For the most part from what I noticed is as follows.
It has very little to do with kills. It has nothing to do with your career stats.
Out of the total 60 players the player who had the best standing from their previous game will be the champion.
I can win a game, then log off for the night and when I log back in in the morning will most likely be the champion.
I have been champion for placing 2nd a few times and once even for placing 3rd with no kills.
When you play with a team and win the champion who had the best overall score on your team is picked.
1) It's not about total kills, it's about total score.
2) Kills+ revives + respawns + damage and so on.
EDITED
That lifeline won it because she healed with her robot and dropped a lot of care packages. Doing such things add to total points.
Traveled distance might even be a factor as well as weapon accuracy.