It is widely accepted that a player who shoots with confidence will shoot the ball at a higher percentage, but from a biomechanics perspective why is this so?
Summation of force is comprised of two main components, sequencing and timing. Ideally each muscle in the sequence (predominantly calves, quads, gluts, core, pecs, anterior deltoid, tricep, wrist flexors) fires as the prior muscle approaches it's peak force generation. I believe when a player shoots with confidence this sequence and timing is more likely to be optimal and therefore the shot is more likely to be accurate. Whereas a player shooting while second guessing themselves is unlikely to get the timing (and perhaps the sequence) optimal as they hesitate and therefore the biomechanical effectiveness of their shot reduces.