Since Blast measures the difference between address and impact (in terms of Loft angle, Lie angle, and Rotation), how the club addresses the ball (sets up) in relation to the ball (and target) makes a big difference.  The further the face of the putter sets up from address, the more prone the sensor will be to “inaccurate”/relative to target numbers. Check your address alignment, and that the sole of the putter is flush with the ground, and visit our Training Center https://blastmotion.com/training-center for drills to improve.