A non-implanted system receives, from an implantable cardiac device implanted within a patient, data corresponding to detected potential episodes of tachycardia. A representation of the data corresponding to the detected potential episodes of tachycardia is displayed to a user, and the user that observes the displayed representation of the data is allowed to enter a user diagnosis for each of the detected potential episodes of tachycardia. The non-implanted system simulates how the implantable cardiac device can use its discriminators to produce device diagnoses, based on the data for the detected potential episodes of tachycardia, including how adjustments to the discriminators affect how the device diagnoses match the user diagnoses. Thereafter, the non-implanted system can reprogram the implantable cardiac device to increase a likelihood that future device diagnoses produced by the implantable cardiac device would more closely match future user diagnoses produced by the user.