Actually it kinda makes sense when you think about it from the point of view of what they accomplished at the times. The time that Ezra had gone undercover as an Imperial cadet he was as far as the galaxy and to Lothal as a whole still a nobody in fact the group as a whole was still a nobody.

the time when Sabine went undercover the crew of the ghost as a whole was far more recognizable especially Ezra because he broadcasted that call to rebellion, dueled with the inquisitors a number of times, has been captured and escaped from Imperial custody a number of times, was responsible for inspiring an unknown number of Imperial prisoners to escape, played a big part in the destruction of a couple of Star Destroyers (One was Grand Moff Tarkin's, the other a prototype gravity well ship), personally faced Darth Vader blade to blade twice, and he had made a lot of progress as a Jedi Padawan. While during this same amount of time Sabine hasn't done that much in regards to the amount of damage she has done to the empire.