A straight changeup is typically the three finger change that has the hand placement similar to the four seam fastball. The thumb and pinky touch and sit on the bottom smooth area right before the seam. The index, middle, and ring fingers will sit across the top of the baseball with the index to the start of the close two-seam. It is best to see the Rawlings sign between the ring and middle fingers.
Pitchers normally tuck the ball in as much possible because the more feel of the fingers and hands, the more movement on the pitch. If a pitcher’s fingers are big and strong enough, they can tuck the ball into their palm using all of pressure on top with palm action to provide rotation resistance.
The straight changeup is the easiest changeup to throw because the hand friction does all of the movement. The pitch should either stay on plane with a reduced speed compared to the fastball, and often the ball can cut down a few inches and drop.