Certain aspects and features relate to a system that determines a result or outcome of a diverter drop in terms of whether far field or near-wellbore bridging, plugging, or diversion has been achieved. The system can provide for real-time measurements and real-time decision making in terms of an optimized diverter to be used in a wellbore. A system for diverter diagnostics can includes a pressure sensor and a processing device communicatively coupled to the pressure sensor. A non-transitory memory device includes instructions that are executable by the processing device to measure an onset of diversion pressure response (DPR) waveform and output or store indications of a result or results of a diverter drop. These results can then be used to adjust a particle size distribution for the diverter.