You can not lost rating if playlock is activated.
Playlock , disable your name from rating , it cut everything , no way for you to loose rating ,ever mind how many times you activate it.

when you want to desactivate the playlock you need to wait that the nextmap is loaded and warmup is over . ( time that TB needs to calculate the map you just plpayed ) IF you desactivate it too ealier , the map will count .
It happened to me 2-3 times .