One of the foundations of what we call "Passive Technique" is the notion that telling a person what they are doing wrong, i.e., identifying "stroke flaws" is ineffective in many cases, and quite often counter-productive. Instead we rely upon building "physical vocabulary", that is, isolated micro-motions that make up the components of an effective swimming stroke when put together.
We believe that humans tend to build upon whatever movement foundation they have, their existing library of motions, garnered from years in the terrestrial environment. By introducing small isolated movements through the use of drills, we can expand that library, and moreover, by using these simple sets of motions we can provide the aspiring swimmer with something "do-able". In other words, we can build from a "position of strength". The converse, what we call the "corrective approach", focuses first on telling the athlete what they are doing wrong, and/or attempts to correct something verbally that is happening amidst a complex set of dynamic motions. But it is so incredibly difficult to achieve this correction within the context of this set of dynamic movements, most individuals fail -- even if the coach has identified the "right flaw".