Interesting problem! I think you might get some improvement if you can isolate the gyro from vibration, as the large accelerations may be disturbing the micro-machined element. Also mounting it at the hand-end of the stick should reduce vibration as the drummer's hands act as elastic dampers to the stick's vibration.
There be other ways to measure this, such as Hall-effect sensors and setting a magnetic field around the drum head, or measuring the position of the other end of the stick relative to the plane of the drum skin...