I love some of the conspiracy theories starting to abound on this topic; they do make for amusing reading.
Please remember that tour lengths are getting shorter (for various reasons including overstretch and the rediculous size of the RAF today) so if people are getting "moved on" it's probably just that they are tourex! The only people who tend to do longer than 2 years in post are aircrew on squadrons, for anyone else (including sqn ldr+ aircrew on squadrons) it will only be about 2 years. It shouldn't come as a surprise that some people have been posted.