Pierre Spey was involved in the development of the F-16 & A-10. 2 very successful programs. I don’t dismiss his criticism lightly. I only hope that he’s far enough removed from the F-35 project that his criticism is wrong.
The F-16 has been successful in spite of its design. It was designed to be a point defense, VFR fighter. Light, agile dogfighter. It has never been used for that in combat.
In combat, it has dropped a lot of bombs. It has a good radar - over the objections of some of the original designers - and a good data link. Current versions are heavier and less maneuverable than the original, but they do the F-16 mission better.
In what capacity? Head shed strap hanger? Considering that they are from two different manufacturers, and had two different system program offices, (both at Wright-Patterson of course), and that they were in development at about the same time, it would have been pretty unusual for one person to be involved in both other than at a "policy" or "oversight" level.