Do you know what the blue highlighted region of the countermovement jump (CMJ) signal is called and what it represents?
This highlighted phase is when the athlete/client drops down or "unweights" and is showing a force lower than body weight because he/she is essentially in free-fall. That is, when you travel the same direction as gravity you will unweight/unload or become lighter.
Can it help your diagnosis?
This phase is important in that if your athlete/client is not able to efficiently unload, the subsequent phases of the CMJ will be affected. Usually the better your client/athlete unweights/unloads, the more efficient the braking and propulsive phases will be. So, it is an important phase to keep an eye on, especially in the injured RTP athlete/client.