The first thing to note is that the first two satellites listed are probably being used in a different way to the newer ones. The fact that they are still in orbit suggests that their payloads are still operating but are maybe being used for some specific tasks rather than the routines of the other two that seem to be fully operational.

KH-11 satellites use sun-synchronous orbits. Looking only at USA 186 and USA 224, it is noteworthy how little the LTDN has changed over the years. KH-11 orbits need periodic orbit boosts to counteract the effects of air drag and maintain the 260 x 1020 kilometre orbit. The boosts also control the position of perigee and the tendency to drift 'off station'. With the two earliest satellites, less control is being exercised over the orbit height so drift in Right Ascension of the Nodes is no longer compensating properly for the Earth's movement round the Sun.

USA 245 is intended initially to work alongside USA 186. Eventually it will take over its duties and USA 186 may take over the rôle of USA 129. The latter may then be sent to a destructive re-entry. Note that the early descending node time for USA 186 is similar to that of USA 129 that it replaced, and the relationship between USA 224 and USA 161 is similar.