I wonder if it's too easy to lose ships in the current state of the game. (compared to say real life or something)
In a real naval battle (let's say... Midway?), 6/19 ships were sunk on the japanese side, while 2/26 were sunk on the US (pulling numbers from wikipedia here, a less than 32 percent casualty rate on the losing side of a battle that's generally considered decisive victory.
Whereas in starsector, a battle would generally involve the destruction of 80+ percent of the losing side while the winning side generally loses nothing
The thing that is most important about Midway isn't how many ships were sunk, it's that Japan failed, and it's what ships were lost. Japan lost its four most experienced aircraft carriers and many of its most experienced naval air crews, it failed in its attempt to take a position which could have made Hawaii untenable or at least made it much more difficult to use Hawaii as a safe haven and forward base for the US fleet, and it failed in its last major offensive in the Pacific.
Also, if you're going to report casualty rates, you might want to consider the type and size of the vessels sunk. Sure, it's 5 of 21 vessels (34 if you count combatants that were not engaged, or 69 if you also include support vessels) by Wikipedia's listing, but those 5 vessels are 4 of 4 fleet carriers and 1 of 2 heavy cruisers (1 of 6 if you count the present-but-not-involved forces). The carriers represent about 43% of the tonnage of the group of ships they were with, depending on how accurate the listed tonnage on Wikipedia is for that engagement and on how accurate the article on the order of battle is, and are 4 of Japan's 21 fleet carriers in service during WWII (according to Wikipedia's page on the Imperial Japanese Navy during WWII). If it had been 4 destroyers that had been sunk out of the carrier group, that could have been as little as 4% of the group's tonnage, and yet it'd still be 20% of the fleet, by number of ships - but they're much less valuable ships. By contrast, the US lost 1 of 3 carriers present and 1 of 15 destroyers - much lighter losses, and also a loss that included a much less valuable and far more easily replaced ship than a heavy cruiser or carrier. When comparing (or considering) losses in a naval battle, it matters a great deal if those 10 ships you lost were all destroyers, or if they were a pair of battleships, three heavy cruisers, a fleet carrier, a light carrier, and three destroyers. Either way, you lost 10 ships - but losing 10 destroyers is usually a much less important loss than losing the 10 ships in the second listing (in particular, it's a much less important loss than losing the first 7 ships in the second listing). Destroyers are much more easily replaced than major warships are.