My memories of Jaques Vallees work was his book on UFO witness reporting, "Anatomy of a phenomenon", back in the sixties.
As was stated in the OP, he was irritated by the official explanations of what eye witnesses reported. For example, even relatively close encounters of objects were dismissed as the planet Venus, etc. I remember one case where two British policemen were chasing a bright object above the tree canopy for some considerable length of time in their squad car, only to be told by MOD
officials later that it was the planet Venus.
As a consequnce he decided to do some research in witness observation of UFOs. This research entailed the examination of a large number of reports which he subjected to statistical analysis to determine whether or not the observations were likely to be real observed close and solid objects, or otherwise.
His final results were published and he concluded from them that the reports did seem to reflect real objects close to the Earth, rather than mistaken remote views of the moon, Venus, weather ballons, and suchlike.
I have to admit myself at that time when so-called "flaps" were going on in Britain in the sixties, that the official explanations when compared to witness statements, seemed rather bizarre and ridiculous. This approach by government did nothing to allay the conspiracy theories that flourished afterwards in the context of these "offical" explanations.