The primary stance is the stance that the catcher will spend the most time in so it’s important that the catcher is balanced and comfortable. The weight should be on the balls of the feet. Even though this is a comfortable stance, the catcher should still be able to subtly shift his/her weight side to side to catch the ball as close to center mass as possible.
The target should always have the glove open as wide as possible. The target height is very important. When the glove is given right between the knees then that is almost always at the bottom of the strike zone. That will help the pitcher execute pitches low in the zone, and that will help a catcher stick a low pitch to ensure that it’s called a strike. It is easier to move the glove up and stick the pitch than it is to move the glove down, and any pitch below the glove is almost always ball so the catcher doesn’t have to worry about presenting that pitch to the umpire.
The glove is the primary target visual, but a big chest facing the pitcher is also helpful. Every visual cue that can help the pitcher execute the pitch well is important to consider.
Different coaches will have different opinions on the “best” location for the right hand. The most important consideration is that it’s safe. Options in addition to the one shown in the picture include under the thigh and tucked into the hip (like the position shown in the secondary stance graphic). The hand should not be behind the back because it is unnecessary and is too unathletic.
The left elbow should always start outside the left knee to make sure that the arm has full freedom of movement to receive the pitch. If the elbow is resting on the knee then the glove hand can become lazy and slow. If the elbow is inside the knee then the catcher will have a hard time catching any ball left of the body with the optimal thumb-under presentation.