In some compositions, the students played fast moving notes very evenly, like automatons while in others - quite chaotically. In both cases, one couldn't feel the pulse of the composition.
The musical pulse is best represented as a regular succession of strong and weak beats in a piece.
Just like a person who doesn't have a pulse is not really alive, in music, too, we need to feel the pulse for the music to breath.
If you ever forget to feel the pulse when you practice, try to count out loud the strong beats of the measure and even subdivide them. This is not very easy but it will allow your playing be perceived as flowing, as having some direction.
Alteration of strong and weak beats helps music come alive.
Transposing Sequence in A minor: vii7-i