First off, MSOCS, you do this forum a disservice by linking to a useless shower of kiddies, mentally ill people, and silly old f**ts posting links to LockMart-supported shill organizations.
Generally: Was Sprey wrong about the F-15? Well, when did the USAF stop buying F-15s that were not primarily bombers? Quite early in the Eagle's career, I think.
Sprey takes a lot of fire for his advocacy of a cold-nose fighter. However, well into the 1980s there was much to be said for the idea that the most lethal air-to-air weapon was still the AIM-9L and equivalents - and today we see the steady rise in the capability of IRST.
RH200 - the F-35 is not "all things to all people" and nor does it offer "diversity of capability". It's dominated by (1) the specific and ill founded requirements of "the navy's army's air force" and (2) the USAF's desire for a stealth deep-strike aircraft, which has meant sacrificing affordability and capability in most of the other missions that fighters are used for.