He’s so good at everything but if you had to pick out his biggest strength it would be his ability to score. He finds a way to get the ball in the hole, and when he misses he still puts it in the best position to salvage the best score he can get.
Mentally, Spieth is very strong and a formidable competitor. he enjoys the heat of the battle and is incredibly resilient. He has the ability to forget and gets over his mistakes quickly which shows his focus on his score.His course management and shot selection is very intelligent and he keeps a cool head under pressure.
He is not an athlete in the mold of Dustin Johnson or Jason Day and if he has a flaw it is that he tries to force his swing to get more distance. His swing involves a lot of hand eye coordination. His grip is very weak and this makes his swing a left sided motion. He doesn’t hit the ball with great speed and so where other players might hit 3 wood off the tee he will use his driver.
His natural shot is a fade and through the ball he tends to go over onto his left foot a lot. He is very accurate and straight. His swing is a stable, compact motion which puts a lot of spin on the ball.
His short game and putting are superior. He chips in a lot and he has a great technique pressing the last three fingers in his grip to keep the club face square and keeping control of distance. He holes so many putts and enjoys practicing his putting.
But most of all as a competitor he is genius level.