Pitch Grips: Fastballs
The four-seam fastball is traditionally the first pitch that every baseball player learns. By putting your index and middle fingers across the four seams of the horseshoe, you get the fastest and straightest pitch a pitcher can throw.
Four-seam fastballs are used to get ahead in the count or to try to get a batter to miss by throwing at high velocity.
The four-seam grip is standard and usually only varies by the distance between the index and middle fingers on top and the thumb’s position on bottom. Both can be changed depending on each athlete’s hand size and comfort level.
Besides velocity, four-seam fastballs can differ in the rate that they spin. Fastballs that spin faster, or have a higher spin rate, get more swings-and-misses as well as more fly balls than those thrown with average spin rate. High-spin fastballs are used best when they are thrown middle or up in the strike zone.
On the other hand, low-spin fastballs get more ground balls than an average-spin fastball. Low-spins are most effective when they are thrown to the middle and lower part of the zone.