KAST is a metric that calculates the contribution of each player per round based on the number of rounds they played. It is basically shorthand for KILLS, ASSISTS, SURVIVED and TRADED.
So can we judge how impactful a player is from his KAST%?
Nahh, its only s out the window. They still can assist and traded offcourse. T means traded not trade your teammates. So if u survive, u not get the T, vice versa. Thats why both duelist or support has same probability for KAST (duelist probably can't get the S, and support probably can't get the T, but if support get the T, they won't get the S)