I'm having trouble following here -- so they realized it was bad against infantry and nerfed it's AI ability anyway?
PTRS use to have very little AI due to low accuracy, even lower than the one Penal now have.
"Guard Troops
Our team determined that as one of the worst rifles/AT in the game, changes to the PTRS were necessary in order to make it a bit more sufficient at its role. Its damage profile remains the same, so damage will still be relative to current values.
PTRS Accuracy increased from 0.03 / 0.0425 / 0.055 to 0.22 / 0.50 / 0.60"
Then typically Relic over buffed
"PTRS rifle
Damage reduced from 40 to 27
13 Bonus damage added vs vehicles"
Then they had to nerf again.