https://apps.dtic.mil/dtic/tr/fulltext/u2/a497264.pdf
This thesis though ten years old provides some interesting thoughts on probability of effective algorithms in determining success of Asroc
MTLS and ASROC – killing the submarine without a helicopter
Certainly this article argues for the use of the VLS system to carry Asroc in the type 26
It surprised me that the type 45 has no torpedoes fitted and can only launch by helicopter.
It also surprised me that the type 26 may be fitted with no torpedoes.
Doesn't the MU90 also have a hard kill option to intercept heavies? Which I guess would be an advantage to still have ship launched torpedoes.
I am going to take a different tack here. Let's say a typical submarine-launched torpedo has a range of around 50km ... but how effective is it really going to be at that range?
Most heavies can be wire guided with a fiberoptic cable, they are quite big units, so actually have a lot of space for sensors and processing.
For them to target a surface ship is fairly trivial. Surface ships only exist in a single plane, the surface, they make heaps of noise, not just from engines, but from wake, waves contacting with hull, and I would imagine there would be quite a bit of noise after they detected a torpedo incoming.
It may be the sub would want it in visual range or at the very least very good audio ranges, maybe they are getting intel and not just randomly sinking any enemy acoustic sounds. Masts are probably 7 nm away max with a periscope. How big is the formation? what is the high value asset you are trying to take out? what capability do they have to get you etc.
This is why its very important to have your enemy acoustically mapped (and yourself). Not just the class, but specific vessels etc. Firing on a sub is several magnitudes harder, particularly if its trying to be unseen.
While ship launched torpedos probably aren't the only solution, they would likely be part of a solution. It no doubt, complicates an attack.
Is your ship alone on a single ship transit/patrol, or part of a taskforce with signficant ASW capability? I think there are many factors you have to consider. Do you have your own subs operating with you? Where are they and what are they doing?