Randomized controlled trials - RCT - are the gold standard in medicine.
The role of these RCT is questionable when it comes to back pain. Back pain is not a homogeneous condition. Causes and circumstances vary, and each person responds differently to a treatment.
As a consequence, a controlled study on non-specific back pain will often conclude in no effect. It is only when patients are categorized, and the cause of pain well identified, that results become positive.
Non-specific exposures, with non-specific treatments, with non-specific back pain guarantee null findings.
A unique person requires individual assessment and treatment. The offending movement that leads to injury can vary from one person to the other.
There is no such thing as “magical recipes” when it comes to manual therapy.