Somehow it appears to me like we have set up a game of shooting fish in a barrel. The pacific theatre seems less appealing than the Atlantic if the odds of destruction is a joke. Of course there could be hidden a new game of frustration if you experience your fish bouncing off the enemy ships time after time.
But I hope Ubi will provide some kind of satisfactory replacement for SH3s many breathless moments where you are going deeper and deeper to avoid the punishment of angry destroyers. I assume the IJN did use destroyers for ASW as well?
54 subs lost doesn't sound like a lot compared to the losses of the Kriegsmarine. But how many subs did USN commit?
[edit] Ah, I found an article about the submarine force here. Less typos, as well

It is worth a read. 288 or so was commissioned, so 52 means it wasn't a complete turkey shoot. Also the IJN did up the escorting during the war, but as with everything else concerning the war against the US, they didn't have the luck nor the power to do something about it.
RESULTS OF THE AMERICAN PACIFIC SUBMARINE CAMPAIGN OF WORLD WAR II