When programming realistic drum patterns, what MIDI parameter is most crucial for simulating the subtle timing imperfections of a live drummer?

The MIDI parameter most crucial for simulating the subtle timing imperfections of a live drummer when programming realistic drum patterns is note start time, also often referred to as timing offset or micro-timing. While velocity (volume), pitch, and note duration are all important MIDI parameters, the precise placement of each drum hit in time is what most effectively conveys a sense of hum....