Just like Timing, there’s also a control in the Groove Pool to determine how much of a groove’s velocity variations are applied to your clips.
Remember that for MIDI clips, Velocity is just a standard MIDI parameter, so unless the instrument is configured to map velocity to volume (or some other parameter) messing with this control won’t have any effect. In the case of audio clips, velocity changes will be mapped to the clip volume automatically.
Bear in mind that some grooves don’t contain any velocity information. (Look inside if you’re not sure).
Also, be aware that Velocity can be set to a negative value, so the values in the groove are inverted.
This can produce some strange and interesting effects.