I dont know if you haven't get into some bug, but i can say that if i am good in something in sh5 WOS, its escaping of DD sonar at 1939-1940
I always go as deep as i can and listen its propellers on hydrophone and track its movement in my mind.
If you track it for a while you could say pretty sure even its turns very precisely..
From manuevers i use only one when you let DD attack you from behind and when you lost his propellers sound at ~180 (its over you), i order flank ahead and turn hard to any side.
In this moment he cannot hear you because you are behind its own motors (and any other cannot hear you too because of the motors of DD above you), so i let flank ahead on for few seconds and change my course.
Then i just order silent run (slowest ahead) or even machine stop and hope they've lost me.
Keep in mind that you are always as "visible" for their sonar as much of you expose to them (you are closest to invisible if you are turn directly to DD or from DD because you expose minimum of your body).
If you are hunted by more DD's at once, it will be very lethal fight for sure and you will have very low chance to escape, because they can cooperate and scan you by sonars in 2D scale (one can detect bearing to you if he detect you, but if second DD do the same from 90 degree, they have your position). Try to escape their depth charges and wait for moment when you can hide behind motor of one of them.. (and hope for a miracle
)