I agree with Markoz here. Having submarines at that state is unacceptable. The problem boils down to the same thing. USN's activities far outstrip fleet size and fleet size in turn far outstrips maintenance resources. Forward deployment is the major cause of this.
The joke is USN needs 3 ships to counter a single threatening lesser ship. One forward deployed, one in the dockyard, one in training/rotation/exercises. This is absolute insanity. They insisted on keeping a third of their navy forward deployed while eliminating smaller combatants and experiencing lower recruitment and budget cuts. And they did that in an era they were unmatched. And nobody in power in the USA questioned the sanity of the navy. That says a lot.
Correction:
Ship rotation is about degree of readiness for deployment in general and has nothing to do with the type of base - home or forward.
ships in rotation | ships in constant readiness | ships in constant deployment |
1 | 0 | 0 |
2 | 1 | 0 |
3 | 1 | 1 |
Those are fleet operating procedures. They've always been like that. This is why ship squadrons have three vessels both in US Navy and in Russian navy and in many other navies.
Forward basing means that USN has a base in theater to eliminate transit from home port and shorten reaction time and reduce dependency on auxiliary fleets for support at sea. Because of that forward bases allow to extend deployment time because ships are not constantly at sea but are in theater. However because forward bases are not home ports and lack maintenance capabilities the ships have to return home from deployment to complete rotation. So forward basing has the downside of extending deployment before maintenance which physically wears down the vessels.
As for elimination of smaller combatants - it was a bureaucratic necessity. Pentagon requires specific amounts of ships with specific capabilities e.g. specific number of missiles on board, radar systems, helos and sonars etc. USN had to choose between retaining cheaper frigates that would lack radar and missiles meaning that for certain missions more than one ship would be required or retaining AEGIS destroyers which had all that Pentagon wanted but were expensive to maintain. In 1990s when the cuts were instituted there was not much choice. USN had OHP frigates and Burke and Spruance destroyers. Spruance would be replaced by new Flight IIA Burke and OHP was partly retired (short-hull) and partly kept in service (long-hull) as OPV. OHPs were meant to be replaced by LCS but LCS turned out to be a disaster which left USN with expensive Burkes for most of operations and only now the gap is being plugged by Constellation.
The problem here has two sides.
Part of it was that USN wanted so many capable capital vessels for primary mission that they needed cheap small vessels for presence and patrol. This ended to be the LCS. If instead they chose smaller number of capital vessels and had new generation of FFGs instead of LCS the problem would have never gotten so serious.
Part of it was also due to over-reliance on allies during Cold War. USN was always seen as the force contributing capital ships while allies were providing support and smaller combatants. After 1991 many of allied countries began to reduce fleets while replacing Cold War designs with more capable larger and more expensive vessels. Coupled with budget cuts it meant that USN lost that allied gap-filler potential which then also became limited by political choices. Cold War deterrence was unanimously supported but American imperialistic adventures were not.
And then there's the problem of being surprised by very rapid Chinese fleet expansion after 2010 - not limited just to PLAN but also to coast guard and "fishing militia". That completely overstretched the forward basing of DDGs and that's why we're here. Under Trump USN was ran completely outside of what it was capable of. INSURV showed consistent declining trend for all vessels in the fleet (except for SSN/SSBNs) due to overuse.
As for nobody questioning the sanity of the Navy... I don't think you can blame it all on the Navy. They wanted more ships, more men and more money but Congress and WH said no. So the Navy said we need fewer missions and Congress and WH said no again. Year after year. Navy has its list of sins but they're not responsible for this mess.
Hope that helped.