OK pigeons here comes the cat.
I've recently finished a tour teaching at the RAF Central Air Traffic Control School.
If you are still reading after the last sentence then you will find out that during the 4 years I was there I was asked to give a presentation to CATC on the way we have separate ground instructors and radar instructors and the benefits therein. During the battle/presentation I mentioned that the quality of student we get has been declining over the 4 years I served at Shawbury and that we get either failed pilots or NATS rejects. I was surprised by the audience reaction to hear that the CATC instructors thought that they were getting the RAFs rejects.
Official or Unofficial, like it or not, There is a perception among many instructors, both military and civil, that the quality of raw student has declined.
To counter this perception at CATCS I had to incorporate into the existing lessons much of the background knowledge that we previously expected the candidate to know through their interest in aviation.
We even initiated a half-day visit to the museum at Cosford so that we could point out the various relevant bits of a jet. (While not on the syllabus it was interesting to note that many of these young RAF Officers couldn't tell a Spitfire from a Hurricane!)
Many more people seem to get through our (RAF) course with the help of extra training. In some cases, people have been taught to pass the course exercises rather than had their natural talent developed and consequently they struggle when they go live. (after only 14 and a half weeks of ATC training!!)