Curl the index finger instead of extending it down the grip
Coaching a student, the coach notes that extending the index (trigger) finger straight down the putter grip - as some pros like Brooks Koepka do - tends to make you flick more. He prefers you curl that finger and connect it a bit more to the ring finger.
Channel: stayhandsy
Watch official source at 3:53Why this context matters
Given while adjusting a student's grip during the on-course coaching segment.