Pitching is as much of a mental game as a physical game. Just because a pitcher has a 98 MPH heater, doesn't mean he is better than a pitcher than someone who tops out at 92. You have to be mentally prepared and mentally tough to be a great pitcher. Mariano Rivera, the all-time saves leader, was one of the toughest players mentally and was never fazed in the ninth inning. Arguably the best postseason pitcher in baseball history, Madison Bumgarner, is never fazed, even with the game-tying run of Game Seven just ninety feet away and the opponent's best power hitter, who already took him deep in Game One.
The pitchers mound is 60 feet 6 inches away from home plate and 10 inches from the ground. There has been debate about removing the pitchers mound and pitching from a flat surface, with the sudden increase of Tommy John surgeries.
Aroldis Chapman has the hardest fastball in baseball history, topping out at 106 MPH in 2016.
There are five different types of fastball, and all have different grips/movement; the four-seam fastball, the two-seam fastball, the cutter, the sinker, and a split-fingered fastball.
Four-seam fastball: the four-seam fastball is the fastest pitch in baseball, but has no horizontal movement. You grip the ball across the "horseshoe seams" with your index and middle finger. Place your thumb directly under the ball, but grip the ball like you would grip an egg. You can throw it overhand, sidearm, or "submarine".
Two-seam fastball: the two-seam fastball is not as fast as a four-seamer, but has more horizontal movement. It is said that two inches of movement is equal to one MPH. So in that sense, a two-seam fastball with 3 inches of movement at 90 MPH is harder to hit than a 95 MPH heater with no movement. The two-seamer is thrown with the index and middle fingers riding the seams that are closer together. Your thumb must be placed under the ball. Grip the ball like an egg. You can throw it overhand, but it has more movement 3/4 or sidearm.